[gnome-control-center] (3 commits) Non-fast-forward update to branch wip/msanchez/printers-clean-heads

[Mario Sanchez Prada <msanchez src gnome org>]

The branch 'wip/msanchez/printers-clean-heads' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  911d2ac... printers: Added stubs for the new action 'Clean Print Heads
  e504769... printers: Added new function pp_maintenance_command_is_supp
  fdd960d... Refactor _pp_maintenance_command_execute_thread to use the 
  d3c18ac... printers: Check all supported CUPS commands, not just the f
  7595e05... printers: Expose the newly added 'Clean' maintenance comman

Commits added to the branch:

  6c36ce7... printers: Added new function pp_maintenance_command_is_supp
  cd96f9b... printers: Check all supported CUPS commands, not just the f
  0da6633... printers: Expose the newly added 'Clean' maintenance comman