Avoid linting untracked files
Avoid linting untracked files

Avoid error running linter after runnning functional
target because it did create some files inside builds/.

Now yamlint will only lint git tracked files, just the
same way it does on infrared repository.

Change-Id: I2fb7f9f0be04440e95ef434dc22e14eafdf1f616

redhat-openstack/octario,redhat-openstack/octario