Strip whitespace from STMP server names.

The STMP server configuration would fail if there was trailing whitespace on the
server name. This was a problem when copy/pasting text into the form.

Testing done:
Produced the bug with an smtp server "smtp.gmail.com     " and triggered an
email event (registration for new user). Log produced an error: "Unknown host".
Added the changes on the diff and tried again, the email is sent and the value
that is saved is stripped of the redudant spaces.

Reviewed at http://reviews.reviewboard.org/r/3759/
Fixes bug 2620.
Fix static media URLs when running the devel server with a SITE_ROOT.

The way that static media URLs ('/static/' and '/media/') were mapped when a
SITE_ROOT was defined was problematic, in that it was appending the SITE_ROOT
twice in the urlspec. The problem is that all the URLs were created with the
root prepended, but the way that settings.py defined the urls didn't have the
right distinctions between the names of the directories and the URL paths.

Testing done:
Tested that loading the dashboard included all static media with a SITE_ROOT of
both '/' and '/example/'.
Merge branch 'release-1.7.x'