Removed support for ReSharper 7.0

(Get the free upgrade to 7.1!)
Stop VSTS DB Pro crashing on VS2010 machines

Fixed #8. Made the 7.1 project .net 4.0 instead of .net 4.5. No idea why, but this causes crashes with VS2010, SQL Server 2012 and when .net 4.5 isn't installed. No useful exceptions, but it all works ok, now.
Now works with NuGet 2.2

Fixes #9. NuGet changed the way it looks for packages in a repository in 2.2. It now uses IPackageLookup, rather than just finding any packages in the repo's directory. It was previously finding the package by luck - we were passing in the package directory, not the repo directory.
Added more visible error handling
Added update available notifications

Closes #10
Bumped version to 1.1