Replace miq-uuid with uuidtools

[djberg96]

As far as I can tell, the only reason to require miq-uuid within this repo is to load the uuidtools library (which is require'd within the miq-uuid.rb file). The MiqUUID module doesn't appear to be used anywhere in this code (it only defines one method - clean_guid), but UUIDTools::UUID.parse_raw is used directly in several places.

So, as part of the ManageIQ/manageiq-gems-pending#231 effort, this PR declares the uuidtools library as a dependency, and updates the various require statements to use uuidtools instead of miq-uuid.