Git extensions plugin

[sc68cal]

I've found the GitExtensions plugin originally written by @roend83 to be incredibly useful, and would like to see it merged. I added a third option to the push menu in the plugin, for the commits to be done with the rcheckin command, since my workflow uses it more often.

[sc68cal]

@ivan-danilov Any progress on reviewing this?

[roend83]

I talked with @spraints about this and we decided that this shouldn't be a part of the git-tfs repository. We decided to create a git-tfs organization and add a new git-tfs-git-extensions-plugin repository. I went ahead and created the repository - https://github.com/git-tfs/git-tfs-gitextensions-plugin. I'll try to get around to pulling this code out and pushing it into the new repository this week.

[sc68cal]

@roend83 - This sounds like a good idea. I use this plugin extensively and want to see this integrated, so I am prepared to do the gruntwork of doing a filter-branch and setting up GitExtensions and Git-tfs as submodules, and do another pull request

[sc68cal]

Went ahead and cleaned up the history and set up the submodule - @roend83 or @spraints can just pull from it and push it into the real repo, since I can't fork an empty Github repo.

[roend83]

I pulled your changes and pushed them into the new repository. Thanks!