Currently these gherkin dictionaries are contained in
`ember-cli-api-double`, which isn't the correct place for them.
They belong with the steps themselves.
This is also less complicated now we can require/import javascript
using a standard approach
Also runs an update of `ember-cli-api-double` which will be the last
installation of version 1 of this module.
* ui: Add ember steps:list command for listing available steps
1. Adds `command` addon to house the new command
2. Start to organize out the steps themselves, bring a bit more order to
things ready to dedupe and cleanup