828 allow room keys change and 827 password attributes to key

Passwords attributes changed to key attributes and now keys are only relevant to the user role, passwords are internal and created for when send_created is called.

refs #827
refs #828
Not wrong, but it doesn't clearly test what has to be tested.
See the suggestion below. The key points are: 1) expecting that `internal_attendee_password` and `internal_moderator_password` are called and 2) expecting the return of these methods to be used in the parameters when calling `send_create`.

```ruby
context "always generate new passwords" do
  let(:moderator_password) { Forgery(:basic).password }
  let(:attendee_password) { Forgery(:basic).password }
  before do
    room.should_receive(:internal_moderator_password).and_return(moderator_password)
    room.should_receive(:internal_attendee_password).and_return(attendee_password)

    params = get_create_params(room)
    params[:attendeePW] = moderator_password
    params[:moderatorPW] = attendee_password
    mocked_api.should_receive(:create_meeting)
      .with(room.name, room.meetingid, params)
      .and_return(hash_create)

    room.stub(:select_server).and_return(mocked_server)
    room.server = mocked_server
  end
  it { room.send_create }
end
```

It looks more like the test "uses #full_logout_url when set" now.