Remove dependency on unittest2 completely
Release version 0.7.3
Add a tox.ini
Merge pull request #9 from mgedmin/toxify

Add a tox.ini
Check calls against function signature.

pyflakes is able to detect some error function calls:
  - too many / too few arguments;
  - unexpected keyword argument;
  - multiple values for single argument;
  - unspecified keyword-only argument (Python 3)