Added initial unit testing files for the pgsql driver.
Save point: WIP implementing db schema functionality.
Savepoint: WIP implementing columns
Savepoint, implementing fkeys.
Added last insert value to pgsql PDO
Savepoint WIP QueryBuilder!
Added table based sequence.
Removed unused columns.
Merge remote branch 'upstream/master' into pgsql-driver
Merge remote branch 'upstream/master' into pgsql-driver
Fixes issue #496
Fixed bug about setting default path aliases.
Renamed Request::getRequestMethod() to Request::getMethod().
Merge branch 'master' of github.com:yiisoft/yii2
moved Pagination and Sort to data.
Added foreign keys and cleanup internal pg types
Merge remote branch 'upstream/master' into pgsql-driver
Added HeaderCollection.
Response WIP
Merge branch 'master' of github.com:yiisoft/yii2