Plugin with support for linking to VisualSVN Server repo browser web interface

Created by: DavidHopkinsFbr

I made a plugin that adds file and diff link button support for linking to the built-in web front-end for VisualSVN Server.

I have permission from my employer to contribute this plugin back into the source-integration project under the existing project MIT licence.

I'm not very experienced with Git or Github, so I'm not sure how I can (or if I should) exclude the documentation changes and sample scripts included in the 53a72cfd commit, which are the same as the contents of PR #311.