LUN-1312, LUN-1313: silenced DoesNotExist exceptions
Merge pull request #30 from pbs/LUN-1312

LUN-1312, LUN-1313: silenced DoesNotExist exceptions
* fixed import error when image does not exists
Stop using mirrors for pip as per PEP449
Merge branch 'master_pbs' into tox

Conflicts:
	tox.ini