Determine if datastore.query.Query.kind should add new kinds to protobuf or overwrite

From TODO:

    # TODO: Do we want this to be additive?
    #       If not, clear the _pb.kind attribute.

See datastore.query.Query.kind for relevant code and #146 for some context.

git blame output

dec0e7c6 (JJ Geewax 2014-01-28 15:15:40 -0500 219)     # TODO: Do we want this to be additive?

Provide feedback