DDL transactions and savepoints for sqlite

Sqlite has had DDL transactions since 2.0.0[1] and savepoints since
3.6.8[2].  This patch updates the connection_adapters.

[1] http://tinyurl.com/sqlite-v2-0-0
[2] http://tinyurl.com/sqlite-v3-6-8

Signed-off-by: Michael Koziarski <michael@koziarski.com>
[#2080 state:committed]

Author: smathy

activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb

@@ -72,10 +72,29 @@ def binary_to_string(value)
     #
     # * <tt>:database</tt> - Path to the database file.
     class SQLiteAdapter < AbstractAdapter
+
+      class Version
+        include Comparable
+        def initialize(vs)
+          @v = vs.split('.').map(&:to_i)
+        end
+        def <=>(rhs)
+          @v <=> rhs.split('.').map(&:to_i)
+        end
+      end
+
       def adapter_name #:nodoc:
         'SQLite'
       end
 
+      def supports_ddl_transactions?
+        sqlite_version >= '2.0.0'
+      end
+
+      def supports_savepoints?
+        sqlite_version >= '3.6.8'
+      end
+
       def supports_migrations? #:nodoc:
         true
       end
@@ -380,7 +399,7 @@ def catch_schema_changes
         end
 
         def sqlite_version
-          @sqlite_version ||= select_value('select sqlite_version(*)')
+          @sqlite_version ||= SQLiteAdapter::Version.new(select_value('select sqlite_version(*)'))
         end
 
         def default_primary_key_type