Attributes passwords renamed to keys.
(models and related things)

refs #827
Room keys changed to external keys, allowing change while a meeting is running.
Added news attributes: moderator_api_password and attendee_moderator_password.

refs #828
Room password is now internal, keys are only for the user role.
Tests done.

refs #828
Fixed things related to internal passwords.

refs #828
Fixed things related to key/password in params.

refs #828
Fixed api_passwords to only be created when they don't exist
Needed to avoid 'already exist meetingId' error.

refs #828
Merge branch '828-allow-room-keys-change' of git://github.com/gmiotto/bigbluebutton_rails into gmiotto-828-allow-room-keys-change

Conflicts:
	spec/models/bigbluebutton_room_spec.rb
Final adjusts for #15, mostly in the tests

refs #827, refs #828
Don't run cucumber on default rake anymore
Merge branch PR #15 from gmiotto/828-allow-room-keys-change

refs #827
refs #828
Review locales and add translation to pt-br
Map keys to internal passwords when generating the join url

refs #827
refs #828