ElasticSearch Simple Query doesn't appear to work

[gaurav]

This doesn't seem to work:

dug/src/dug/core/async_search.py

Lines 228 to 229 in 99d6130

	if self.is_simple_search_query(query):
	search_body = self.get_simple_concept_search_query(query)

e.g. searching for pain -chronic doesn't filter out chronic pain.