Slightly better types

Dash now supports a lot of new entry types. For example, previously,
modules were indexed as "Categories", Dash now supports a "Module"
entry type. The full list of entry types can be found at
http://kapeli.com/docsets/.
Use py.test's tmpdir feature
Update dependencies

Also use dev-requirements.txt in tox.ini.
Update HISTORY, add AUTHORS & CONTRIBUTING
Bump version
Fix pydoctor link
properly install deps for tox invocations
Don't use mirrors in Travis

CDN is faster.