Read parent tree into the index before applying changes
Rename UpdateTfsHead and new purpose for UpdateRef
Compute base changeset Id
Unshelve based on the parent changeset Id
Fix Fetch for initial commit
Replace git command update-ref by a LibGit2Sharp call to UpdateRef()
Refactored PerformRCheckin

- Common checks are still in the base method
- 'Quick' specific code is in _PerformRCheckinQuick
- the non-Quick code is in _PferformRCheckin
GitCommit can now return (forward) Sha of the wrapped commit.
RCheckin now has correct author attribution in quick mode too.

+ Refactored PerformRCheckin to remove duplicate code
Introduce FindCommonGitCommit

Instead of relying on the base changeset IDs coming from the shelveset,
the first git commit that is found to contain the exact SHA1 for all
the files in the shelveset is used as the parent.
Update libgit2sharp.
Eliminate `Process.Start("git", "update-ref", ...)`
Update libgit2sharp to include libgit2/libgit2sharp#421
Use the new refs API.

Thanks @Saaman!!!!
Show CheckinTool window in task bar
Share ParentForm between Vs2010 and Vs11 projects
Merge pull request #360 from pmiossec/checkintool_visible_taskbar

Show CheckinTool window in task bar. Closes #359
Apply fix for Vs2008
416543 Fix: git-tfs tries to authenticate against all TFS instances in the branch no matter how old they were in use and if they needed at all.
Merge pull request #361 from spraints/update-ref

Replace Process.Start with libgit2sharp. (closes #360)
Merge pull request #362 from EPashkin/fix-git-tfs-authenticates-against-all-tfs-instances_vs2008

Apply fix for Vs2008