undefined method `task' for #<MyApp::Application:0x000001012d3be0>
It turns out that the new version of rake is broken, and it is automatically updated when you run bundle. Since that's the case, we need to roll back to v 0.8.7. I found some resources with different recommendations for fixes, but following is what worked for me:
First, we need to uninstall rake 0.9.0. In your terminal, type gem uninstall rake -v 0.9
Open your Gemfile. Add the following line gem 'rake', '~> 0.8.7'
Go back to your terminal and type bundle update rake.
Run your migration!