do not add tagged series into tree index
do not add tagged series into tree index

this also means that they don't need to be deleted in the delete()
method, because the delete() method is only for series without tags.

raintank/raintank-metric,replay/metrictank,raintank/metrictank,replay/metrictank,replay/metrictank,raintank/metrictank,raintank/raintank-metric,raintank/raintank-metric,replay/metrictank,raintank/metrictank,raintank/metrictank