* Add comment option to authorized_keys
* Update version_added for authorized_keys comment
* PEP8
* Include index rank in parsed_key_key
* Properly display diff
Only display diff if specificed via settings
* Fix PEP8 test failure
Removed from legacy files since it is now properly formatted
* Cleanup integration test formatting and add test for new comment feature
* Correct version_added for new option
* Refactoring: split readkeys() into readfile() and parsekeys()
* Refactoring: split writekeys() into writefile() and serialize()
* authorized_key: support --diff
* Refactoring: remove no-longer used readkeys()/writekeys()
* Integration test for authorized_key in check mode
