Added missing methods:
CollectionHandler -> checksum and revision
Database -> listUserDatabases
DocumentHandler -> head and added revision parameter to getById
Added missing methods:
Connection, enabled headers
DocumentHandler, added head and fixed get
EdgeHandler, chaned calls to not use inherited calls from documentHandler
GraphHandler, added getVertices and getEdges
new JobHandler,
CollectionHandler, new Methods, first, last, fullext
deleted JobHandler, created base methods that can be shared by edge and document handler. fixed documentation errors