Tweaked Scaladoc of *Like traits, adding that I do override toString in the
* subclasses. Also added the missing toString override in the path traits.
Added clarification on the difference between Failed and FailedStatus, and
Succeeded and SucceededStatus to their Scaladoc. Added a comment to
Framework to indicate it is a work in progress for sbt 0.13. Added
a boilerplate Scaladoc comment to the top of MatcherWords.