1056760: Support guestids with reverse-endianness

Any time we query for a host or guest consumer record given
a uuid type identifier, attempt using both the id as given
as well as a transformed uuid where the first three sections
are reversed-endian
Example:
78d7e200-b7d6-4cfe-b7a9-5700e8094df3
will be searched, as well as:
00e2d778-d6b7-fe4c-b7a9-5700e8094df3
Leverage spec test to verify guest consumer to host lookup
Merge pull request #611 from candlepin/ckozak/virt_uuid_hotfix

1056760: Support guestids with reverse-endianness