Switch TravisLint to use travis gem

The `travis-lint` gem is deprecated in favor of `travis`.

Change-Id: I66f76739d780b90dad3426759ab45946eab14237
Reviewed-on: http://gerrit.causes.com/45347
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>