Import error after upgrade to OMEMO 0.9.8

Bug description

Gajim raises an Import Error for module Image everytime the OMEMO configuration window gets opened. Happens after upgrade to OMEMO 0.9.8. Gajim still works, no crash happens, it just pops up the window everytime configs are opened.

Steps to reproduce

• Open Gajim
• Go to: Edit->Plugins->OMEMO->Configure
• Error is displayed
• Go to "Clear Device" tab and click refresh, error is displayed everytime "Refresh" is clicked
• Import Error is:

Traceback (most recent call last):
  File "/home/xxxx/.local/share/gajim/plugins/omemo/ui.py", line 520, in refresh_button_clicked_cb
    self.update_context_list()
  File "/home/xxxx/.local/share/gajim/plugins/omemo/ui.py", line 624, in update_context_list
    gajim.get_jid_from_account(account), deviceid, ownfpr[2:])
  File "/home/xxxx/.local/share/gajim/plugins/omemo/ui.py", line 405, in get_qrcode
    img = qr.make_image()
  File "/home/xxxx/.local/share/gajim/plugins/omemo/qrcode/main.py", line 275, in make_image
    self.border, self.modules_count, self.box_size, **kwargs)
  File "/home/xxxx/.local/share/gajim/plugins/omemo/qrcode/image/base.py", line 13, in __init__
    self._img = self.new_image(**kwargs)
  File "/home/xxxx/.local/share/gajim/plugins/omemo/qrcode/image/pil.py", line 33, in new_image                                                                                              
    img = Image.new(mode, (self.pixel_size, self.pixel_size), back_color)
  File "/usr/lib/python2.7/site-packages/gajim/common/demandimport.py", line 86, in __getattribute__
    self._load()
  File "/usr/lib/python2.7/site-packages/gajim/common/demandimport.py", line 58, in _load
    mod = _origimport(head, globals, locals)
ImportError: No module named Image

Software versions

• OS version: Archlinux
• GTK version: 2.24.31
• PyGTK version: 2.24.0