handled RegisterResponses

added toString to DeregisterRequest
handled deregister responses
added list messaging nodes command to Registry

made handling of command line nicer
created MessagingNodesList

moved NodeInfo to be its own class
handled sending and receiving of MessagingNodesList
added assignment of link weights when setting up overlay + command to
print out link weights at Registry

added makefile

added command to print out current peers at MessagingNode
added classes for Dijkstra's
added handling of link weights message and command to print out shortest
paths in MessagingNode