flexitest refactor

* controller is an absolute Layout
Merge branch 'master' of github.com:Heigvd/Wegas

# By Francois-Xavier Aeberhard
# Via Francois-Xavier Aeberhard
* 'master' of github.com:Heigvd/Wegas:
  Add update event on clearCache() call in Y.Plugin.DataSourceREST
  Refactor: splitted Y.Wegas.App, created with Y.Wegas.Helper class