Make tests compatible with Django 1.3
Added tox config for Python 2.6, 2.7 and Django 1.3 and Django 1.4
Removed verify_exists from FiberURLValidator to make it compatible with Django 1.5
Added Django 1.5 to tox config
Added python 2.7 and multiple Django versions to the Travis config
Updated test requirements: coverage==3.6 and django-jenkins==0.14.0
Merge pull request #157 from mbraak/tox

Test multiple Django and Python versions on Travis ci; also added tox support - This is great, thanks Marco!