Remove StackOverflow badge
Make forum link optional

Only include the link to the forum if the project has one
Only display the API doc link if the project has API docs

This is something of a hack at the moment. The right border on the
reference doc link has been removed. This border provides a separator
between the reference doc link and the API doc link. It’s fine for the
platform as it has no API docs but it’s not a general solution.