Merge branch 'pgsql-driver'
Force travis to create a postgresql test database
Removed conditional pgsql env
Fixes issue #514.
Merge remote branch 'upstream/master'
Multilevel Items
Removed unused columsn from find constraint sql. Fixed typo. Added extra schema check for when a foreign table is not in the same schema. Updated indentation to conform to other classes.
Updated code style. braces on the same line for control statements.
Merge pull request #516 from m-o-g/master

Multilevel Nav items
[1] Redone missing code.
[2] Added empty line at the end of file
[3] Removed exception.
- Ported addPrimaryKey and created dropConstraint.
- The dropConstraint method can be used both for dropPrimaryKey and dropForeignKey
Merge pull request #517 from gevik/pgsql-small-fix

Pgsql small fix  (update 2)
Unit test for "yii\console\controllers\MessageController" has been created.
Replaced dropConstraint with dropPrimarykey method.
Exception usage has been added to "yii\console\controllers\MessageController".
coding style fix.
Action "template" has been added to "yii\console\controllers\MessageController".
Default action of "yii\console\controllers\MessageController" has been renamed to "generate".
Response WIP
Merge branch 'master' of github.com:yiisoft/yii2