Remove call to undefined install.post_process()

Oslo commit b5cca99e5281d9c0c5eda444137e418b31209c45 removed
the obsolete redhat-eventlet.patch.  Part of this commit
removed the post_process() method which we were still calling
in tools/install_venv.py .  The post_process function was just
there to do any distro-specific post processing.  By default,
that was nothing.  So, this is safe to remove.

This same change was made to python-novaclient with
commit 0194492059920fd8d9d91849c341b2de0b561089 .

Closes-bug: 1275025
Change-Id: I4c52e2c0d3d6553f5d33e94cd6e8622160febc37
Remove vim header

Making this change for python-cinderclient to be consistent
with Cinder.  The same change was made to Cinder via
commit ff3f2e5735f0d486b72b6881b05ace94d6d34d03 .

Partial-bug 1229324
Change-Id: I69fb960f499f0c9a9c9671d46d10170477cf6695
Merge "Remove call to undefined install.post_process()"
Merge "Remove vim header"