Removed SkipList Code

-moved SkipList Code out to its own project
Edited Comments in PriorityQueue

-removed references to min heap from Priority Queue
Refactored Push

-instead of passing in an HNode push accepts a key and a value
Added Houtput Class

-added data container class so that Huffman Encoder can return the
encoded string as well as the tree that produced it (for decoding
purposes)