Improved exception handling at MapiSessionHandler
Calendars are now aware of Openchange connection
Tasks are now aware of Openchange connection failure

 * Also corrected some indexing
Improved logging features to zentyal_oc_login plugin

 * Also some code cleaning
Custom logout procedure when profile creation fails

 * Custom error message, avoiding the "you have successfully logout"
   when the user actually wanted to log into Roundcube
Added openchange connection error message in 3 languages
Added warning to the user when Openchange server is not present
Tasklist: added warning to the user when Openchange server is not present
Added translated message errors
Contacts now are aware of Openchange server failure
Added changelog file
Merge pull request #7 from Zentyal/mjulian/exception-handling

Mjulian/exception handling