add _utils make_start_key and make_end_key to replace padding options on join_uuids, should work with non-uuid keys
s/join_uuids/join_key_fragments/g , except cassandra sometimes
join_uuids becomes simpler, no padding.
Merge remote-tracking branch 'origin/switch-to-instance-collection' into nonuuid-swtic

Conflicts:
	kvlayer/tests/test_accumulo.py
Merge remote-tracking branch 'origin/master' into nonuuid-swtic
link to github issue