Added initial code for calculating weights between different nodes.
Added initial file for checking weights between paths.
Renamed method 'weightOfPath' to 'findPath' which is a more accurate representation of what the method should (eventually) do.
Cleaned up the callback test so it's easier to read.
Added new dependency (lodash), and also attempted to hack the graph so its now directionless. Finally, added the distance lookup table for calculating the distance between nodes.
Added lodash dependency.