Support for Sqlserver2014

This adds a stub for Sql Server 2014 support. A new SqlServer2014ProcessorFactory means that the
provider/db argument to the runner now accepts the string SqlServer2014.

A new SqlServer2014Generator class is added too but all it does is inherit from the SqlServer2012Generator without adding any new functionality.

The integration tests can also be run against Sql Server 2014.

I had look at what's new with Sql Server 2014 and I couldn't see any new general features like sequences in Sql Server 2012. There is a change to columnstore indexes: http://msdn.microsoft.com/en-us/library/dn511016.aspx but that's about it. Am I missing something important? Azure stuff maybe?