Removed ActorContext spike.
Fixed missing require in Channel.
Correctly fixed missing require in Channel.
Merge pull request #87 from jdantonio/removed-actor-context-spike

Removed ActorContext spike.
Add 4 convenience methods to obligation

wait - waits and returns self
no_error! - waits and raises on rejection, otherwise returns self
value! - returns value, or raises if rejected
exception - allows to call `raise rejected_ivar`
Add Observable#with_observer returning self
Add documentation
Raw port of Actress

needs more work and discussions
Change Abstract actor class to a ActorContext module
Remove Algebrick dependency
when spawn returns children are set
Reject all envelops sent to termiated actor before actor is GCed
Remove dead code
Remove dependency on Atomic
Remove unused mutex

no instance variables are being reassigned
Add Reference#ask!
TODOs and comments update