Add ability to specify and run post upload hooks

tests/git_cl_test.py

Index: tests/git_cl_test.py
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index 94cd662637fe8a56a2be880b04f1aabeffb54355..ed29824002424311ae2480c347356287be99f7bf 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -221,6 +221,7 @@ class TestGitCl(TestCase):
         ((['git', 'symbolic-ref', 'HEAD'],), 'hash'),
         ((['git',
            'config', 'branch.hash.last-upload-hash', 'hash'],), ''),
+        ((['git', 'config', 'rietveld.run-post-upload-hook'],), ''),
     ]
 
   @staticmethod
@@ -731,6 +732,8 @@ class TestGitCl(TestCase):
            'rietveld.project'],), ''),
         ((['git', 'config', '--unset-all',
            'rietveld.pending-ref-prefix'],), ''),
+        ((['git', 'config', '--unset-all',
+           'rietveld.run-post-upload-hook'],), ''),
         ((['git', 'config', 'gerrit.host',
            'gerrit.chromium.org'],), ''),
         # DownloadHooks(False)
@@ -758,6 +761,8 @@ class TestGitCl(TestCase):
         # DownloadHooks(True)
         ((['git', 'config', 'rietveld.bug-prefix'],), ''),
         (('Bug Prefix:',), ''),
+        ((['git', 'config', 'rietveld.run-post-upload-hook'],), ''),
+        (('Run Post Upload Hook:',), ''),
         ((commit_msg_path, os.X_OK,), True),
         ]
     git_cl.main(['config'])