Add Changelog for 2.0.3
Add Changelog for 2.0.3

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