-Added checks and improved error message from can_publish() and publishing failures.- returned can_publish() to its former glory.
A list of errors will be presented to the user when they run 'rbt publish ##'

validate_can_publish(self, errors=False) has been added. passing true will generate an exception whereas false or default will only return a boolean if it is a valid review request having a reviewer, summary, and description.
--Merged Review Request with request 7882

TODO: create automated test

    test publish with user + summary fails

    test publish with user + description fails

    test publish with group + summary fails

    test publish with group + description fails