Improve whitespace around css and script tags
Remove reference to the `config` variable in the template files
Add support for extra_css and extra_javascript in all the themes
Avoid repeated overwrites of config['extra_*']

Fixes #133
Merge pull request #136 from jimporter/config-var

Remove reference to the `config` variable in the template files for custom themes
Merge pull request #90 from jimporter/extra-css

Add support for extra_css and extra_javascript in all the themes
Merge pull request #134 from dnrce/bug/133-wrong-extra-media-paths

Avoid repeated overwrites of config['extra_*']
Merge pull request #135 from dnrce/extra-media-whitespace

Improve whitespace around css and script tags
Use Tox to run the tests on Travis

Rather than repeating the steps in the Travis config, use Travis to run
tox. This has the added benifit of verifying the setup.py install into a
virtualenv.
Removed flake8 exclusion that wasn't needed
Merge pull request #125 from d0ugal/travis-updates

Use Tox to run the tests on Travis
Support multiple template directories

theme_dir is now a list which contains the user provided directory if
given plus the packaged theme directory.

Fixes #129