Bump NPM version to 0.4.20 in preparation for publishing.
Bump NPM version to 0.4.20 in preparation for publishing.

shumov/recast,kyldvs/recast,cpojer/recast,marcioj/recast,ersengultepe/recast,rwaldron/recast,benjamn/recast,fkling/recast,ipeychev/recast,stefanpenner/recast,kassens/recast,benjamn/recast,benjamn/recast