contrib/vstudio cleanup

Hi,

the contrib/vstudio stuff is a bit off a mess that I just cleaned up.

The vc10 directory contained files from the IDE used to save user settings, which shouldn't be commited.

The vc11 directory contained a pretty strange project that seems like a mix from VS2010 and 2012. It also only contained build configs for the zlib DLL in x64 mode only. And it tried to connect to someones private Team Foundation Server for source control.

The vc12 directory contained a proper VC11 / VS2012 project, just is in a wrongly named directory (should be vc11).

So I deleted the vc11 directory and renamed vc12 to vc 11.