Split off some content previously placed into base back into index.html.
Move content previously localised in accounts_home to a new content_base
for use in the non-app version of the site.
We wrote up some copy and styled it according to taste.
In our new signup form, we no longer collect a short name and instead
extrapolate from the email.
(imported from commit cd734b13a4bda7f304129379524c4cc96b77b24b)
In this commit we also remove the navbar from base.html for implementing
further changes as requested by Waseem.
(imported from commit 85a8ea82ff0e271120adde83e15eb671b5584722)