Fixes bug #966242
The version_control command is a bit useless since you can't actually
specify what version to use and it defaults to version=0.
Allow the user to specify a version:
$> glance-manage version_control 9 # set the diablo version
and default to the latest version if none is specified.
Also, allow db_sync to be supplied a version for the case where we're
upgrading an unversioned DB.
Finally, re-work the argument handling in glance-manage to more easily
handle optional args.
The tests are extended to test using db_sync for upgrades and to test
placing an existing database under version control.
Change-Id: I231dc710554198bfd1fdcb82c3c3768963f64bd8
2f9eba10e0