Don't allow --allinone and --answer file together.

Change-Id: Ie689e719176a55e2f40c224c0df6f8dadc852413
Fixes: rhbz#957761
Disable glance caching.

Change-Id: Idc926684fb08e10568c7a4b6fa02feaa97408fd9
Fixes: rhbz#947611
Merge "Don't allow --allinone and --answer file together."
Merge "Disable glance caching."