Merge pull request #2 from mwisnicki/patch/vs2012-merged

Undo VS2010/VS2012 project split and use conditional elements when neede...
Automate build and move DLLs under libs. Now Release output can be ignored too.
Fix tests on NET4.0, update nunit to 2.6.
Run tests with single nunit runner (in separate processes).
Add "Test" target.
Initial nuget support. Just drop nuspec on build.cmd to create.
Remove nuget.exe download scripts and assume it is in PATH.
Fix nuget build and add relevant files to solution.
Update nuget versions.
Copy runtime files only into executable projects.