Drop MANIFEST.in - it's not needed with PBR

Zaqar uses PBR already - as you can see setup.py:

 setuptools.setup(
     setup_requires=['pbr>=1.8'],
     pbr=True)

PBR generates a sensible manifest from git files
and some standard files.
So, this removes the need for an explicit
‘MANIFEST.in’ file.

Change-Id: I6f3aa562345cb055fe7f1dae49dac3720222764f
ref: http://docs.openstack.org/developer/pbr/#what-it-does

MANIFEST.in

@@ -1,6 +0,0 @@
-recursive-include zaqar *.lua
-
-exclude .gitignore
-exclude .gitreview
-
-global-exclude *.pyc