Merge pull request #1540 from ngokevin/iarcerr

show error msg if content rating info invalid (bug 948524)
Merge pull request #1544 from ngokevin/iarcgrace

msg notifiying devs app will be disabled on 4/15 if no ratings (bug 950245)
don't show required step on top of detail submit step, show diff. msg if app is public w/o ratings