Remove terminal handling in libcontainer

Allocating the ptys are not needed inside the api right now.  The can be handled in the create method for a container.  We will have to add this in the new api when it's ready but for now I think we can push this to the caller above us and have them pass the stdin,out,and err that we need.  

Fixes #95

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
I'm trying to find the golang docs on what interfaces actually are.  They are special in the language and you should never have a pointer to an interface.  Interfaces themselves are pointers to the underlying type that is why you can always pass `nil` instead of an interface value.