Add `PostTimeout` function to allow us to instruct go-notify to timeout after a specific time.Duration for event channels that are blocking.
Don't duplicate the "E_NOT_FOUND" error string, and don't perform (relatively slow) map lookup more often than you have to.
Added `StopAll` function to close all of the listeners on a given event.
Merge pull request #1 from rafrombrc/master

Add `PostTimeout` function