Modified to don't let users choose a username/permalink/param equal to a used one.

Sometimes a user/space can be disabled, but after a while they can be enabled again. So to avoid the problem generated by duplicate identifiers users can't choose a username/permalink/param equal to one disabled.

refs #609
A few more logs and tests on ShibbolethController

Pulled from mconf-rnp/mconf-web
Add a few custom abilities when testing Space

Pulled from mconf-rnp/mconf-web
Some tests to ensure the uniqueness of username/permalink/param.

refs #609
Update bigbluebutton_rails, fix setting the "record" flag