Added support for implements and extends of GeneratedType;

Added functionality to store List of implementing Generation Types into
GeneratedType and GeneratedTypeBuilder;
Added functionality to store Extending Transfer Object for
GeneratedTransferObject and GeneratedTOBuilder;

Fixed:
DataNodeIterator no longer returns augmented containers, lists, leafs
and leaflists - only non augmented module schema tree;
Added findDataSchemaNode for given SchemaPath into SchemaContextUtil;

Signed-off-by: Lukas Sedlak <lsedlak@cisco.com>