Tests: add pytest support
Travis: install pytest-cov and pytest-django before running script
Travis: update py.test
Tests: include py.test support in setup.py
Test: use django-setuptest for handling test via 'setup.py test'
Setup: clean-up dependency_links and remove dependency on django-dynamic-formset
Test: back to pytest-django
Travis: pip 1.5 does not allow dependency-links by default

Quoting Pip changelog:
    BACKWARD INCOMPATIBLE pip no longer respects dependency links by default. Users may opt into respecting them again using --process-dependency-links.
Travis: fix django settings for test
Merge dj1.6 into dj1.6-tests