Bump NPM version to 0.8.20 in preparation for publishing.
Bump NPM version to 0.8.20 in preparation for publishing.

facebook/regenerator,facebook/regenerator,rafaelstz/regenerator,RReverser/js-goto-transpiler,sebmck/regenerator,liviuignat/regenerator,sebmck/regenerator,juliocanares/regenerator,kittens/regenerator,RReverser/js-goto-transpiler,liviuignat/regenerator,rafaelstz/regenerator,kittens/regenerator,juliocanares/regenerator,facebook/regenerator