Basic groundwork for Akismet implementation.

Some API design, mockup integration and templates.
Basic Akismet implementation.

Only for spam checking for now as we don't have any way to classified
comment as spam or ham in the website. `akismet.ham` is now
`akismet.spam` to match the return value of "comment-check" API.
Send application name and version back to Akismet per document.

As required by Akismet API. As a result, version is now exposed via
`fanboi2.__VERSION__` instead of only define it in setup.py.
Add test case for Akismet integration.

We're avoiding HTTP requests by using Mock to mock requests object and
mock the Akismet.spam method itself in views.
Merge branch 'feature/akismet' into develop