Update permalink_fu to fix an error when logging in via federation

If the user's name passed to the application was not in UTF-8 it would make
permalink_fu break when creating the user's login.
Fix wrong full name set to users on shibboleth login

Was using references to strings in the session when creating a new user. Some
of these strings would be changed internally in the User model and data in
the session would change as well, making the user's full name be actually set
to the value of his login.
Fix error introduced by 5343a3830, refs #973

The variables could be nil and then cloning it would throw an error.
Fix error when anon users try to create meetings, refs #1021

When an anonymous user tried to create a web conference using the moderator
password in the invite view, the application was crashing because `current_user`
is nil.
Fix private message text for webconf invitations, refs #1020

Wasn't sending the message written by the user when sending the invitation
via private message. Via email was sending it correctly.
Fix wrong message in space invitation emails, refs #984

Was sending the message in the wrong language in some cases, and in some cases
using more than one language in the same email.
This was in the email sent to the admins of a space confirming that a user
accepted or rejected an invitation to join the space.
Remove option to invite people to spaces via email only

It doesn't behave properly and it's not a feature worth reimplemeting right
now. Invitations to join spaces now can only be sent to users that are
registered on Mconf-Web.

Only removed the fields from the invitation form, everything else is still
there.
Merge remote-tracking branch 'upstream/master'