Fix plugin exit when user's not authenticated

Previously the check was done on the instance of Player, which will not
be None since we pass the constructor.

Instead, we add a boolean is_logged attribute to the MyEpisodes object
and check that.
Remove login function

There was no point having a login function since we need to call it,
whatever happens.
This is now done in the init of MyEpisodes object.
Update Regex expressions

Again stolen update from XBMC Subtitles.