Cap GitPython at 2.1.1 due to performance degradation

It appears newer versions of GitPython have slowed considerably.
Cap GitPython until gitpython-developers/GitPython#605
is resolved.

Change-Id: Ie6c8722e8b607bb50e77fbad59e18363616f7e0d
Signed-off-by: Paul Belanger <[email protected]>
Signed-off-by: Jamie Lennox <[email protected]>
(cherry picked from commit 7b3f3be)

Author: pabelanger

requirements.txt

@@ -7,7 +7,7 @@ PyYAML>=3.1.0
 Paste<2.0
 WebOb>=1.2.3
 paramiko>=1.8.0,<2.0.0
-GitPython>=0.3.3
+GitPython>=0.3.3,<2.1.2
 ordereddict
 python-daemon>=2.0.4,<2.1.0
 extras