/category/add: DuplicateKeyException when name differs from existing only by case

[php-coder]

Steps to reproduce:

• create category with name test
• try to create another category with name Test

Right now it fails because we're trying to insert non-unique slug:

Caused by: org.springframework.dao.DuplicateKeyException: PreparedStatementCallback; SQL [INSERT INTO categories ( name , name_ru , slug , created_at , created_by , updated_at , updated_by ) VALUES ( ? , ? , ? , ? , ? , ? , ? )]; Unique index or primary key violation: "UC_CATEGORIES_SLUG_INDEX_6 ON PUBLIC.CATEGORIES(SLUG) VALUES ('test', 5)"; SQL statement:
INSERT INTO categories ( name , name_ru , slug , created_at , created_by , updated_at , updated_by ) VALUES ( ? , ? , ? , ? , ? , ? , ? ) [23505-192]; nested exception is org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "UC_CATEGORIES_SLUG_INDEX_6 ON PUBLIC.CATEGORIES(SLUG) VALUES ('test', 5)"; SQL statement:
INSERT INTO categories ( name , name_ru , slug , created_at , created_by , updated_at , updated_by ) VALUES ( ? , ? , ? , ? , ? , ? , ? ) [23505-192]
    at org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator.doTranslate(SQLErrorCodeSQLExceptionTranslator.java:239)
    at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:73)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:645)
    at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:900)
    at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.update(NamedParameterJdbcTemplate.java:318)
    at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.update(NamedParameterJdbcTemplate.java:299)
    at ru.mystamps.web.dao.impl.JdbcCategoryDao.add(JdbcCategoryDao.java:87)
    at ru.mystamps.web.service.CategoryServiceImpl.add(CategoryServiceImpl.java:76)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:68)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
    at com.sun.proxy.$Proxy139.add(Unknown Source)
    at ru.mystamps.web.controller.CategoryController.processInput(CategoryController.java:85)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
    ... 67 more
Caused by: org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "UC_CATEGORIES_SLUG_INDEX_6 ON PUBLIC.CATEGORIES(SLUG) VALUES ('test', 5)"; SQL statement:
INSERT INTO categories ( name , name_ru , slug , created_at , created_by , updated_at , updated_by ) VALUES ( ? , ? , ? , ? , ? , ? , ? ) [23505-192]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
    at org.h2.message.DbException.get(DbException.java:179)
    at org.h2.message.DbException.get(DbException.java:155)
    at org.h2.index.BaseIndex.getDuplicateKeyException(BaseIndex.java:103)
    at org.h2.mvstore.db.MVSecondaryIndex.checkUnique(MVSecondaryIndex.java:231)
    at org.h2.mvstore.db.MVSecondaryIndex.add(MVSecondaryIndex.java:190)
    at org.h2.mvstore.db.MVTable.addRow(MVTable.java:704)
    at org.h2.command.dml.Insert.insertRows(Insert.java:156)
    at org.h2.command.dml.Insert.update(Insert.java:114)
    at org.h2.command.CommandContainer.update(CommandContainer.java:98)
    at org.h2.command.Command.executeUpdate(Command.java:258)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:160)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:146)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:105)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:105)
    at org.springframework.jdbc.core.JdbcTemplate$3.doInPreparedStatement(JdbcTemplate.java:903)
    at org.springframework.jdbc.core.JdbcTemplate$3.doInPreparedStatement(JdbcTemplate.java:900)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:629)
    ... 101 more

[php-coder]

It started to throw exception after fixing #206 when slug became a unique field. Before it was allowed to create two countries that names differ only by case (which is also a bug and probably even worst).