test(inspec): switch tests to use Inspec

[daks]

After discussion on slack, a PR to switch to tests with Inspec. Those are basics, testing pkg/file/service.
General CI config copied from https://github.com/saltstack-formulas/template-formula/ master, so commitlint included.

[javierbertoli]

Awesome. I'd probably remove the test/salt/default/pillar/nginx.sls and Gemfile.lock files?

[aboe76]

@daks, wow nice work, and I concur with @javierbertoli

[daks]

Files removed or emptied.

[daks]

CentOS 7 test disabled for now, but it's still better than no tests at all 🍾

[myii]

@daks Merged -- thanks for fixing the tests in this formula. A very impressive job, as we've already discussed on Slack. Just to bring across the important notes here:

• Left semantic-release (and commitlint) for a future PR.
• Used the newest testing matrix from salt-formula instead of the template-formula, as based on this merged PR by @javierbertoli: Update the testing matrix (5 distros, 2 python versions, 3 salt versions) salt-formula#406.
• Disabled the Salt version-specific test suites for the time being (using default throughout) -- need to create an issue to remind us that this work is still needed.
• Commented out centos-7 because it is currently failing (on the salt-formula as well, since around 4 days ago) -- Daniel mentioned probably due to work being done on releasing python3.6 versions of salt for centos 7 -- need to create an issue to retest this in the next week or so.