karma: misc updates

* don't tarpit queue hook (might have a poor interaction with smtp_client)
* don't trap rejections from spamassassin (which is very configurable)
* add missing 'plugin' in a loginfo()
* fix a couple broken karma.ini rules
* punctuation changes
* karma.ini: add connect.fcrdns.generic_rdns = -1
Tiny gripe - but isn't this better as two switch() {} blocks (e.g. O(1) rather than O(n)) as indexOf is going to have to traverse the entire array and compare each element.   The effect is going to be tiny as this is such a small array, but I hate using Array.indexOf() unless really necessary.