Email: Correct swedish translations

The previous translation of "forward" to "framåt" is
normally correct, but not in the context of Email clients.

(Fix for issue 24485 and 22117.)

The previous translation of the Invite tab is also a literal
translation that doesn't match the intended meaning.

(Fix for issue 25379.)

Change-Id: I831485dfb7dc258cee2b1f4bec8ed9d8dc1394b8