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.

flake8 --select W391,E302,E301,E304

autopep8 can't fix W391 even though it claims it can.
Fixed using a simple custom script.

Remove useless trailing \
Remove trailing spaces
Add missing empty lines

autopep8 -ir -j2 --select=E301,E302,E502,W291,W293,W391 .

Diff quickly checked.