Relax version bounds so both 0.15 and 0.16 theoretically work.
Relax version bounds so both 0.15 and 0.16 theoretically work.

rtfeldman/node-elm-test,rtfeldman/node-elm-test,ento/node-elm-test,avh4/node-elm-test,ento/node-elm-test,rtfeldman/node-test-runner,avh4/node-elm-test