There were a few items missed with the patch enabling changing
WEBROOT patch.
First the XStatic files were being unpacked in the wrong directoy
because root_url was not being passed in. This caused 404 errors
when running with a different web root.
This change allows root_url to be passed in on XStatic handling.
Second, STATIC_URL and MEDIA_URL were not using WEBROOT.
These now are built with WEBROOT.
Third, the fa-font-path variable was hard-coded in _variables.scss
to use "/" as the web root.
A webroot variable has been added that can be overridden. Additionally,
a new theme has also been added to change the web root.
Closes-Bug: #1434276
Change-Id: Ifff1c60b3405ce2136d039b8d74da08752e7215c
18dddd97da