Move from gem-based to a regular theme

[cseas]

Part of the discussion in #2

We're trying to create a very customised website for which we might not find a gem-based theme that just works out of the box. Hence, the theme should be migrated to a regular one from a gem-based one.

[asdofindia]

Another reason to include all theme files in the repo is that new contributors can directly edit the theme then.

We just have to make sure the theme we are using has a permissive license.

[karx]

We can close this now.

[asdofindia]

Thanks @karx. Closing. Giving you triage access.