Initial MSSQL related commit.
allow unit tests to requireApp() on setUp()
mod: don't create app in bootstrap script, unit tests do it themselves
add: option to destroy app after each test to find unit tests that fail
     to require an app
add: new key for unit tests config named "className". Allows to run the tests
     using different Application instances (consoleApp/ webApp)
mod: TestCase::getParam accepts second param $default=null
mod: incorporate suggestions
- rename requireApp() to mockApplication()
- always destroy app on tearDown()
  - eliminates need for constant YII_DESTROY_APP_ON_TEARDOWN
  - mockApplication() becomes a lot easier. Destroying app on each tearDown
    means creating it on every call is fine. No more checking if it already
    exists and if it has been created from the same config.
- \yii::$app should have been \Yii::$app
Merge branch 'master' of github.com:yiisoft/yii2 into mssql

Conflicts:
	yii/db/Connection.php
MSSQL driver classes moved to the proper location.
RBAC: Item and Assignment optimized save approach
MSSQL table metadata parsint (initial version).
RBAC: DbManager code style fixes
RBAC: DbManager code style fixes
MSSQL Schema: methods order changed, initial data type infer.
Initial MSSQL tests.
CS fixes.
Merge branch 'master' of github.com:yiisoft/yii2

Conflicts:
	apps/bootstrap/index.php
	yii/yiic.php
Change magic property to normal method. (Thanks to @maxlapko.)
CS fixes.
CS fixes.
Travis-CI build status.
Merge branch 'master' of github.com:yiisoft/yii2 into mssql