yesod-auth: send json responses
Merge branch 'master' into auth-json-2

Conflicts:
	yesod-auth/Yesod/Auth.hs
	yesod-auth/Yesod/Auth/Email.hs
	yesod-auth/yesod-auth.cabal
Merge pull request #700 from yesodweb/auth-json-2

Auth json 2