#24 Rules seem to be marked as modified when they should not be

[Jonathan Baker]

Rules are currently marked as modified when a comment that the rule references is modified. If the comment is modified the rule should NOT be marked as modified since nothing specific to the rule changed.

This may also be an issue for:
- references
- internal checks
- compliance checks
- how-tos

This becomes an issue in the rt ui when representing the last modified date to users. a user would expect that an edit to a commend would make the rule appear modified.