Fix VS2010 solution and tests to be at least SQL Server 2008 compatible

I've just now updated to VS 2012, but before doing so I realised that the VS 2010 solution was pretty messed up.

I'm not sure if there's any desire to keep it reasonably maintained for people who are only targeting 3.5/4.0, but if so I've gone ahead and cleaned things up, including changing the 4.0 target test project to actually target and work with 4.0.

There was also a test case which was a response to [a Stack Overflow question reporting a non-bug](http://stackoverflow.com/questions/16726709/string-format-with-sql-wildcard-causing-dapper-query-to-break) that can only ever work against SQL Server 2012. For lack of a better solution, I put in a version check to prevent the test from throwing an exception when the statement isn't expected to work to begin with.