Remove setuptools_git from setup_requires.

This is a mistake for the case where someone is using setup.py from a tarball.
We need it installed for sdist making only, which is why it's in test-requires.

Change-Id: Ib79cbe3e638c0772325872d4bb30be26c7b91391

setup.py

@@ -73,8 +73,6 @@ setuptools.setup(
 
     test_suite='nose.collector',
 
-    setup_requires=['setuptools-git>=0.4'],
-
     scripts=['bin/ceilometer-agent-compute',
              'bin/ceilometer-agent-central',
              'bin/ceilometer-api',