Added argument checking for user_id

  Fixed apparently uncommitted change

   pre-setting done in page_contract had been ignored in some cases

  Added im_hour_nuke function in order to destroy logged hours
  for the REST interface

  if uses modify already submitted hours

  Fixed issue with determining if the WF is installed

  Fixed permissions for absence logging

  Fixed issue with wrong user_selection lists for timesheet
  vs. absences

  Renamed add_hours_for_direct_reports into add_hours_direct_reports

  Covered the case that the absence doesn't yet exist

  middle managers to see the timesheet for their
  direct reports

  Removed rounding of weekly sum hours

  Now maintains modifying_user

  - Fixed display of "Group Absences", so that users can
    see the absences of their offices for example
  - Fixed "mine" selection

  Fixed issue with creator of a group absences included in group

  Now removing absence_owner_id when creating a group absence

  Fixed im_absence_status and im_absence_type_xx -> im_user_absence_xxx

-- Show absences of direct reports

  Exended the selection of group to im_biz_office_groups

  Renamed im_absence_type_* into im_user_absence_*

  Now including the members of departments,
  if the current_user is a department manager

  Extended the "view_absences_direct_reports" privilege.
  It now also includes the members of the user's department,
  if he or she is a manager of a dept.

  Modified rules to show Edit and Delete buttons, so that
  absences without WF control can be modified by their creators