moved the Store interface to a real key/value store
checking the KeyName names
removed an unnecessary implicit
added a method to return all direct prefix keys from a given key
added a method to check if a prefix exists
added a listDropRightOne method on store to list the parent keys of leaves
removed the listDropRightOne method
keep the original URI in the location
removed the URI component of Location
Merge pull request #44 from ambiata/topic/store-keys

Moved the Store interface to a real key/value store