ReSharper 8 support

Very minor changes to get AgUnit working with ReSharper 8.

* Clean compile
* Added nuspec file for extension gallery
* Nuspec file not necessarily correct - missing icon, and took liberty of adding your name as author and owner :grinning: 
* Removed version info from plugin attributes. Didn't bump version number, since no changes made

Looks like it works nicely with a simple compile! Any chance of a new build and getting the extension uploaded to the gallery, please? Note that if you're building against 8.0.1 or 8.0.2 binaries, the package should take a dependency on ReSharper >= 8.0.1000 or 8.0.2000, or the binary references will fail at runtime.