Fix #1364: Reduce the presence of hard-coded SR links.

This allows for development alongside other SR services
at a completely separte URL. The remaining srobo.org urls
are present as defaults or placeholders.

Change-Id: Ifdb4adfd1b4aae991824e8b89501966d310aa61e
Don't work out the extension manually.

Change-Id: I30a39ac08173ce00286e5a42ab5c32b3a49382ac
Don't try to remove a folder whilst in it.

We'll see this folder again as a listing in the parent,
from where it makes more sense to try to remove it.
This also ensures that we won't ever try to remove the
root folder that we're iterating through, and avoids a
PHP error from trying to remove something that ends in '/.'

Change-Id: I5c0dbf24964ab3c868db7c17743326c3caa6a2f4
Allow empty commit messages.

It appears that the previous mechanism for achieving this
no longer works, probably because git strips trailing
whitespace from commits. Fix this by using --allow-empty-message
and add a test.

Change-Id: I3f8206af541301950dca5c098b47d69ff3f487dd