Added VertexCollection
Graph: Add vertex collections to the graph
Graph: Fetch a single VertexCollection
Added CollectionNotInGraphException
VertexCollection: Raise an exception if the graph does not know the collection yet
Graph: Add method to check if a collection is part of the graph
Graph: Actually loading the vertex collections
Graph: Added revision attribute
Graph: Return the actual edge collections
Graph: Expose the edge definitions
Graph: Refactored graph instantiation
Collection: Added deprecation for `create_edge`
EdgeCollection: Added basic implementation
Faraday: Handle gharial specific 404 correctly
The graph object is nested in the response
Graph: Initialize orphan and edge collections with non nil
Graph: Keys are camelCase