Correct misspelt word in msg in test_images.py

msg = ("The container format and the disk format don't match. "
       "Contaiter format: %(container)s, Disk format: %(disk)s." %
       {'container': container_format, 'disk': disk_format})

    "Contaiter" should be "Container"

Change-Id: Ib8b3fae328fb004ee367b19ed41385b1d325fb46
Closes-Bug: #1580823
1 file changed