match nodes using labels
revert back to single string get-by-index query
tidy +tests
use match_clauses where possible
whitespace
more tests
PersistableType doesn't go in the db
-dev version bump
whitespace
typo
find a uniqe attr with a not-None value
Merge remote-tracking branch 'origin/master' into label_matching

Conflicts:
	CHANGES
	setup.py
final version
Merge pull request #115 from onefinestay/label_matching

add (and use) get_match_clause