We should use always our own driver
Added username to our driver creation
Added tasks handling to MapiSession
Tasks listing and creation almost working

 * Based on the "database driver", will be changing function by
   function.
 * First version of the tasks parsing class
Dates are now processed before saving them to the OC server
A task can now be edited

 * Also, user timezone is taken into account when parsing dates
Some user-timezone issues solved

 * The OC server still stores the time with -1hour, so for now,
   I've done a quick-hating fix
Tasks deletion
Some type-juggling to fix properties behaviours
Tasks completeness improvements
Implemented count_tasks

 * If tasks have already been retrieved, we don't fetch them again
 * But if forceUpdate is TRUE (after task creation)
Task filtering
Fixed search filter
Fix get_task wasn't finding any task due to 'force' param
UI => disable add/edit tasklist buttons
Merge pull request #3 from Zentyal/mjulian/tasks

Mjulian/tasks