For future Python 3 compatibility.

Add the support of www.residentadvisor.net, a calendar of clubbing event.
Inherits of CapCalendarEvent and offers the following :
  - search event by date and city
  - (un)attend to event if credentials are supplied

A function search_events_by_title is implemented in ResidentadvisorBrowser,
although not used, in hope that this functionality becomes possible in a near
futur.