Use tox to run tests against Django versions 1.5, 1.6 and 1.7.

The tests fail against 1.5 and 1.7.
Fixed runtests.py to work with Django 1.7 and removed tests for number of queries.
Merge pull request #11 from davidwtbuxton/tox-tests

Tox tests
Bump up version number
Small documentation fix for use of '{% ifswitch %}' template tag.
Ignore product directories for `tox` and `./setup.py sdist`.
Merge pull request #12 from davidwtbuxton/doc-tweaks

Doc tweaks