[gnome-control-center] (28 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:

  abab6c2... printers: use panel-wide page for empty-state
  f2ac5a8... printers: enforce the empty-state patterns
  3ba4fcf... printers: present spinner while populating the panel
  c0f2073... printers: introduce PpPrinterEntry widget
  fb4b0a5... printers: introduce PpDetailsDialog
  5da4253... printers: Added new async API to check availability of main
  a77f744... printers: Check all supported CUPS commands, not just the f
  017c691... printers: Expose the newly added 'Clean' maintenance comman

Commits added to the branch:

  b756290... Updated Spanish translation (*)
  d1329f1... user-accounts: add space between rows in um-user-panel (*)
  5e2ed8e... user-accounts: hide language settings for current user (*)
  de0de51... user-accounts: split join-dialog from account-dialog (*)
  1db970e... user-accounts: port "Add User" dialog to gtk+ composite wid (*)
  09cbc05... user-accounts: move Add User dialog buttons to ui file (*)
  af13556... user-accounts: move spinner to header in Add User dialog (*)
  4d001f7... sharing: Update "Media Sharing" dialog description (*)
  612ac49... sharing: Update "Screen Sharing" dialog description (*)
  8b68961... sharing: Use a checkbutton in the "Screen Sharing" dialog (*)
  8e414f8... sharing: Move "Remote Login" switch to headerbar (*)
  27ce5b3... shell-model: introduce new categories (*)
  2777fd5... panels: use the new categories (*)
  cb1e0c4... panel-list: create a custom class to handle the sidelist (*)
  11ce397... window: adapt to use CcPanelList (*)
  45d6073... window: remove the placeholder view (*)
  908f483... Updated POTFILES.in (*)
  f3b7c16... sharing: Drop the "Personal" from "Personal File Sharing" (*)
  da1d8f0... sharing: Update "Remote Login" dialog description (*)
  11dd608... printers: use panel-wide page for empty-state (*)
  8c71b0b... printers: enforce the empty-state patterns (*)
  93f71e5... printers: present spinner while populating the panel (*)
  8d1bf74... printers: introduce PpPrinterEntry widget (*)
  0cd5ca4... printers: introduce PpDetailsDialog (*)
  4df6903... printers: Added new async API to check availability of main
  24d728a... printers: Check all supported CUPS commands, not just the f
  2502066... Migrate the remaining bits of PpMaintenanceCommand to GTask
  30b28f0... printers: Expose the newly added 'Clean' maintenance comman

(*) This commit already existed in another branch; no separate mail sent