Add changelog for upcoming 2.2.0
Add changelog for upcoming 2.2.0

suryasnath/Venture,WellframeInc/jbuilder,rails/jbuilder,maclover7/jbuilder,jasnow/jbuilder,sue445/jbuilder,ASnow/jbuilder,vincentwoo/jbuilder,nambrot/jbuilder,odedniv/jbuilder