GitHub Pane fails to parse URLs for repositories with '.' in their name

[grokys]

On current master, opening a PR in for example https://github.com/haf/DotNetZip.Semverd fails with:

System.NotSupportedException occurred
  HResult=-2146233067
  Message=Unrecognised GitHub pane URL: /haf/DotNetZip.Semverd/pull/104
  Source=GitHub.App
  StackTrace:
       at GitHub.ViewModels.GitHubPane.GitHubPaneViewModel.<NavigateTo>d__43.MoveNext() in D:\projects\VisualStudio\src\GitHub.App\ViewModels\GitHubPane\GitHubPaneViewModel.cs:line 253
  InnerException: 

This is because the pullUri regex doesn't accept periods in repository names.