Add GitHub Pages Jekyll configuration

In order to take advantage of Jekyll on GitHub, simulate the version and
configuration used there.
Automatically generate the meetings lists

Switch to using Liquid templates for the homepage and move the actual
meeting information into a Jekyll data file.

At the moment, this isn't hugely different to the static version but
with the data and presentation separated, we can hopefully start to do
more interesting things (particularly if we attach more metadata to the
meetings such as books discussed).
Remove comma from date format
Add README and Procfile to ease development
Use Jekyll to generate the meeting list

Introduce Jekyll and Liquid templating to help with the later issues
which will likely require using layouts and includes.

The main example here is lifting the actual meeting information into a
separate Jekyll data file [1] which is then used to automatically
generate the list on the front page. I was hoping that we could even
dynamically separate past and future meetings with a filter [2] but alas
that doesn't seem possible and it would only change when we pushed
changes to the site anyway.

We can then use a similar pattern for a list of members and make it
trivial to add yourself without having to get involved in the actual
page design.

Closes #8.

[1] http://jekyllrb.com/docs/datafiles/
[2] http://jekyllrb.com/docs/templates/#filters