Add new variation of TreeFilter in order to detect LFS pointer files in
the repository.
Additionally, update LfsPointer to support the legacy version URL [1] as
described in [2], and to allow arbitrary fields in the pointer file.
[1] https://hawser.github.com/spec/v1
[2] https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
Change-Id: I621eb058619fb1b78888a54c4b60bb110a722fc3
Signed-off-by: Dariusz Luksza <dariusz@luksza.org>
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>