Bug 1025451: Strip redhat vendor from cartridge names

At present, the OpenShift REST API won't return the vendor as part of the cartridge name
for cartridges whose vendor is `redhat`. To properly validate these cartridges against
the cartridge specified by `builderType` (which now contains vendor information, even
for redhat cartridges), strip `redhat` from cartridge names prior to validation.

This workaround can be removed in the future when the REST API returns vendor information
as a separate field associated with a cartridge during list requests.