MonadTell and MonadListen typeclasses
cleaning
added trampolined Future, and Task, which extends Future with error handling
added Catchable typeclass, a context in which exceptions can be caught and thrown
Merge pull request #293 from YoEight/topic/writer

MonadTell and MonadListen typeclasses
Fix Validation forall description
Merge pull request #297 from ceedubs/validation-forall-doc

Fix Validation forall description
added unit test for Task and made some minor API tweaks
merged
guarding Now(x) flatMap f with More to avoid SOE
add apply to Cokleisli
re #295 NEL → Nel
Merge pull request #298 from folone/scalaz-seven

re #295 NEL → Nel