Add promise/fetch polyfills
Add promise/fetch polyfills

Fixes IE11

kidaa/codecombat,javatlacati/codecombat,jeremiahyan/codecombat,codecombat/codecombat,icodegame/codecombat,icodegame/codecombat,kidaa/codecombat,jeremiahyan/codecombat,jeremiahyan/codecombat,kidaa/codecombat,javatlacati/codecombat,icodegame/codecombat,codecombat/codecombat,codecombat/codecombat,codecombat/codecombat,codecombat/codecombat,javatlacati/codecombat,javatlacati/codecombat,javatlacati/codecombat,jeremiahyan/codecombat,kidaa/codecombat,icodegame/codecombat