Cache the connection we use to clean the DB with (Take 2)

The connection caching was a little bit too liberal and was caching
across databases (I think). No we just grab it when we enter clean.

Added an iterator so there isn't too much code duplication between
delete and truncate.

lib/database_cleaner/active_record/deletion.rb

@@ -53,10 +53,8 @@ module DatabaseCleaner::ActiveRecord
   class Deletion < Truncation
 
     def clean
-      connection.disable_referential_integrity do
-        tables_to_truncate.each do |table_name|
-          connection.delete_table table_name
-        end
+      each_table do |connection, table_name|
+        connection.delete_table table_name
       end
     end
 

lib/database_cleaner/active_record/truncation.rb

@@ -103,24 +103,26 @@ class Truncation
     include ::DatabaseCleaner::Generic::Truncation
 
     def clean
+      each_table do |connection, table_name|
+        connection.truncate_table table_name
+      end
+    end
+
+    def each_table
+      connection = connection_klass.connection
       connection.disable_referential_integrity do
-        tables_to_truncate.each do |table_name|
-          connection.truncate_table table_name
+        tables_to_truncate(connection).each do |table_name|
+          yield connection, table_name
         end
       end
     end
 
     private
 
-    def tables_to_truncate
+    def tables_to_truncate(connection)
        (@only || connection.tables) - @tables_to_exclude - connection.views
     end
 
-    def connection
-       #::ActiveRecord::Base.connection
-       @connection ||= connection_klass.connection
-    end
-
     # overwritten
     def migration_storage_name
       'schema_migrations'