If spec helper is available it will run the rake
task that is included in [1] otherwise it will
install metadata-json-lint and run it manually
like the other lint things does.
Only runs if the metadata.json file is available
so should not require any changes in modules if
something is wrong there.
[1] https://review.openstack.org/591605
Depends-On: https://review.openstack.org/591605
Change-Id: I60571e919e95327bf56a61bc33298a3810b942f7
60967dee60