correct flatten of annotation filter arrays
correct flatten of annotation filter arrays

Previously we were incorrectly converting annotations to facet filters
due to single-value annotations being flattened to their individual data
members (e.g. [:category, name, value] enumerated as :category, name,
value).

HACK fix - single-value annotations are in a nested array to thwart the
flat_map

OpenBEL/openbel-server,OpenBEL/openbel-server,nbargnesi/openbel-server,OpenBEL/openbel-api,OpenBEL/openbel-api,OpenBEL/openbel-api,nbargnesi/openbel-server,nbargnesi/openbel-server,OpenBEL/openbel-api,OpenBEL/openbel-server