Add extra handling to highstate outputter for 'Comment'

[basepi]

Highstate outputter was handling strings in the comment, and lists, but wouldn't handle anything else. (In this case, the fix is for dicts, but it should fix for any data structure, assuming it has a defined string representation)

Really, states should not be outputting comments as dicts, and this may not look especially pretty, but it will not stacktrace and fallback to the default outputter. It will be up to the authors of those states to fix their comments to make them pretty.

Fixes #12840

[ghost]

Test Failed.

If the failures are unrelated to your code, don't stress, a core developer will know these apart.
In the future, if possible, please branch off a passing commit to avoid false positives.
Refer to this link for build results: http://jenkins.saltstack.com/job/salt-pr-build/4425/

[basepi]

Failures unrelated to my code.