get_response should not crash the connection (#142)
get_response should not crash the connection (#142)

* get_response should not crash the connection

`lists:keyfind` might return false if the id does not exist. For
instance through multiple calls to `h2_connection:get_response`.

* Use get_from_subset instead
joedevivo/chatterbox,tsloughter/chatterbox,tsloughter/chatterbox,joedevivo/chatterbox