3.0 add before_test scripts for appveyor

Solves the following error causing random test failure on appveyor:
``Msg 922, Level 14, State 1, Server APPVYR-WIN20122\SQL2012SP1,``
``Database 'model' is being recovered. Waiting until recovery is finished.``

A ticket is open on [AppVeyor issue tracker](http://help.appveyor.com/discussions/suggestions/264-database-mssqlsystemresource-is-being-recovered-waiting-for-sql-server-to-start) and this script also comes from this issue.