NuGet Package : Add repository metadata.

[MaximRouiller]

Basically, we can now add a repository metadata on a nuspec file to allow the repository to be surfaced on NuGet. This allows you to have a projectUrl as well a repository URL now.

I've talked about it on Twitter but the most basic things to know is here:

NuSpec Reference

Reference Implementation in Json .NET

[mikkelbu]

This issue should be closed by #175.

[OsirisTerje]

Yep, wasn't aware of this. Normally I do the merging and updates the docs at the same time. I'll add this one in.