Removed RESOLVING and REJECTING
Deferred's throw an error if resolved/rejected more than once
Rejected handlers which return a value call a chained promise's resolved handler
and callbacks are not required - if they're not code refs they are ignored
Tidied
Fixed version check in skip clause in t/050-exceptions-pp.t
Removed more resolving/rejecting
May as well remove when() as well
Fix _notify to work with the Deferred backends
Updated tests to all pass with new code
Merge pull request #23 from clintongormley/master

Conform to Promises A+