[SAC] UserID Mantra request page

A user just joined #osgeo-sac complaining that
the "Request mantra via email" button did not work
and there was no indication of the actual email to
use.

This happens when browsers have a misconfigured
handler for "mailto" links, so it is a good idea
to also make the email visible.

For now I've updated the page to show the email
in the button text, please take a look:
https://www.osgeo.org/cgi-bin/ldap_create_user.py

Still, the text in that button cannot be copied
to clipboard, which may be another barrier for
someone.

So, if anyone has ideas for further improving
that page (which may also benefit from including
the new logo, for instance) please send a patch.

NOTE: SAC members should be also able to send
      a pull request against
      https://git.osgeo.org/gogs/sac/web-cgi-bin

--strk;