Update whipper release number in init.py

I'm going to tag this as a new amended version 0.5.1: no changes were done apart from the version number bugfix.
I've also included a code coverage report.

Fixes #147

morituri/__init__.py

@@ -2,7 +2,7 @@ import logging
 import os
 import sys
 
-__version__ = '0.4.2'
+__version__ = '0.5.1'
 
 level = logging.WARNING
 if 'WHIPPER_DEBUG' in os.environ: