Autocomplete should be regenerated after installing or removing plugins

[stof]

Do you want to request a feature or report a bug?

feature request

What is the current behavior?

After installing a plugin, its commands are not available in the autocomplete

What is the expected behavior?

Commands are available in the autocomplete list automatically.

[k80bowman]

Just to add some more details here, in order to update the autocomplete list after installing a plugin I had to:

• Run heroku:autocomplete --refresh-cache to build a new autocomplete cache
• Open a new terminal window/tab