compare_results.py: show rule ID in case one of results is "not applicable"

#### Share the context

This was discovered when comparing results gained from scans with our content versus scans with DISA provided SCAP.

#### Description of problem:

In case where one of results (in this case OUR rule) results in "not applicable", I can't see the rule ID of that rule. I can get CCE or STIG ID... but that requires me to grep the content repository to get to the particular rule.

#### Proposed change:

Output the rule ID of not applicable rule.