Added SHA-1 performance test
Added peer disconnect detection closes #35

* `Peers` now provide a send() and onmessage() interface instead of
using the datachannel property directly
* Peers send heartbeats at a configurable rate to detect failing peers
* Turned off default debugging for Chord Router
* Fixed tests
Incorporated heartbeat feedback refs #35
Minor changes to Peer class; added Chord tests

* The Error thrown from Peer.send() now contains the actual cause
Removed unused variable from Node class
First steps towards an URI-based API