rake assets:precompile
Revert "rake assets:precompile"

This reverts commit 6528d75ad6ddde70c36012079141a71ef3d75180.
heroku slug precompile assets fail
add configuration in production.rb to see the result
https://devcenter.heroku.com/articles/rails-asset-pipeline
config.assets.initialize_on_precompile = false
  because heroku's automatically assets:precompile failed,
  this line should be added by heroku documentation
  https://devcenter.heroku.com/articles/rails-asset-pipeline
  I added it to environments/production.rb before, but still failed
  let try to add it to application.rb
  config.assets.initialize_on_precompile = false
because heroku cannot do assests:precompile correctly. I must do it locally and add git.
add ruby 2.0.0 to gemfile
rake assets:precompile:all RAILS_ENV=development RAILS_GROUPS=assets