Count_occurrences doesn't correctly track regular expressions

[OliverSherouse]

quantgov/quantgov/corpora/builtins.py

Line 123 in 5c22c6e

+ tuple(term_counts[i] for i in terms)

We need the term_counts dictionary keys to be the actual regexes, not the string matches. We should map the one to the other and then generates results from the remapped version.