Graph: Added #delete method
Graph: Adding edge definition
Graph: Get a single edge collection from the database
cleaning up the Graph-spec a bit
Graph: Cleaning up some code
EdgeCollection: Adding directed relations
EdgeCollection: Return edges on #add method
Graphs: Removed unirectional example from acceptance spec
EdgeCollection: Overwrite #send_request_for_this_collection to use gharial
Collection: Extracted method to build the content class
Edge: Allow passing a graph
EdgeCollection: Added #remove (by example)
Graph: Added #neighbors method