Running `make dev` runs `hclfmt`, but this isn't checked as part of
CI. That makes it possible to merge un-formatted HCL and Nomad
jobspecs that later will make for dirty git staging areas when
developers pull master.
This changeset adds HCL linting to the `make check` target.
Before, the proxy stanza did not parse non-object fields
`local_service_port` and `local_service_address` from the
connect `proxy` stanza. This change fixes that.