This PR switches the Nomad repository from using govendor to Go modules
for managing dependencies. Aspects of the Nomad workflow remain pretty
much the same. The usual Makefile targets should continue to work as
they always did. The API submodule simply defers to the parent Nomad
version on the repository, keeping the semantics of API versioning that
currently exists.
* changes necessary to support oss licesning shims
revert nomad fmt changes
update test to work with enterprise changes
update tests to work with new ent enforcements
make check
update cas test to use scheduler algorithm
back out preemption changes
add comments
* remove unused method
