Nicely format the environment when opening "update" view

[january3]

Editing / updating the container environment JSON is always a bit of a hassle, because the JSON is presented on one line, which makes it hard to navigate and edit. However, when the container is simply viewed, the JSON is nicely formatted.

I suggest that the same formatting should be used for the "update" view text area with the environment. That would make editing the containers way easier.

[stolpeo]

https://kevinmickey.github.io/django-prettyjson/