Update() fixed for case when file cannot be checkout from TFS
GetRootChangesetForBranch catch VersionControlException
VersionControlException exception handling improved
Init branch crash fixed if branch already exist (big problem with `branch --init --all`)
Better perf by caching branch list

Conflicts:
	GitTfs.VsCommon/TfsHelper.PostVs2010.Common.cs
Ask Tfs server tfs branches only once
Retry on timeout
GetChangesets()  asks changesets by parts
ParseEntries()  called only when really needed
Garbage collection added to `clone` and `branch --all` commands
ReadIdentity crash fixed
HasWorkItems crash fixed
Support resume interrupted clone
Because the directory exit don't assure that the git repository have been initialized

ex: git tfs clone [...] .
Check latest changesets first
Apply() moved after ProcessMergeChangeset()