Add back service lookup by barclamp name

The cherry picked commit d55963f459e658cdc7121f63edac52c3213820a2
references Service class lookup by barclamp name that was refactored in
stoney in 290b00bd14a5cea26f77bf169e326848c55ced2e as it was no longer
used.

Add back the service lookup.
Refactor Kernel.const_get("#{barclamp}Service")

ServiceObject now has its own function to do just that.
Merge pull request #1002 from bkutil/add_back_missing_service_lookup

Add back missing service lookup