Fix `exon` reductions for 2 field alleles#322

mmaiers-nmdp merged 2 commits intonmdp-bioinformatics:masternmdp-bioinformatics/py-ard:masterfrom

pbashyal-nmdp:exon_redux_with_wpbashyal-nmdp/py-ard:exon_redux_with_wCopy head branch name to clipboard