use `rails_12factor`
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
do not use exception_notification

we are using errbit
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku
Merge branch 'master' into heroku

Conflicts:
	Gemfile.lock
`bundle`
Merge branch 'master' into heroku
Merge branch 'master' into heroku