Prepare for 0.1.3 release

[sjperkins]

• [x] Tests added / passed
• [x] Fully documented, including HISTORY.rst for all changes and one of the docs/*-api.rst files for new API

Howto run test cases and lint the code base

```bash $ py.test --flake8 -v -s tricolour ``` If you encounter flake8 failures, a quick way to correct this is to run `autopep8` and `flake8` again. ```bash $ pip install -U autopep8 $ autopep8 -r -i tricolour $ flake8 tricolour ```

Howto build the documentation

To build the docs locally: ```bash $ pip install -r requirements.readthedocs.txt $ cd docs $ READTHEDOCS=True make html ```

[sjperkins]

I've been using bump2version to automatically change setup.py and create the git tag. However, we've sensibly protected master branch.

So I think we should merge this PR and tag the related commit in master.