Starting to implement the PersistentHashMap
empty map should not contain key 0
Allow to add null keys to empty map
Allow to add some elements to the map
Can add tons of key value pairs
Handle hash collisions
can add lots of keys with colliding hashes to empty map
Allow to lookup items from a map
Allow to remove items from the map
Merge pull request #10 from forki/Map

Starting to implement the PersistentHashMap