Refactored id handling by making system types a separate id space and distinguishing from user types.
Renamed SystemType to BaseType to make SystemType generic and allow for ImplicitKey to be added
Merge branch 'titan05' of https://github.com/thinkaurelius/titan into titan05
Throwing exception when setting implicit type
Updated classes to correctly handle implicit keys
Abstract planning for allowing the passing of meta data to the storage backend for each Entry captured in WriteEntry
Reworked serialization so that the user no longer has to differentiate between byte order preserving and non-preserving data types.