Codeplex-1163 - Improved error message for duplicate named attribute
routes.

Duplicate names for traditional routes already give a good error message,
which explains that you can't do that, and what the duplicate name is.
Prior to this change duplicate names on attribute routes would fail with a
generic 'duplicate key' message without telling you the key.
Fixing an FxCop break
Parallelize code for creating attribute routes in MVC and Web API.
Fix current WSR build break
- Were apparently not downloading packages from MyGet.org
- Use package sources listed in NuGet.config