Allow extra config to be controlled by environment variables

[typhonius]

Is your feature request related to a problem? Please describe.
We have added in environment variables for Acquia key and secret, it would be useful to also have other config items based on environment variables e.g. timezone.

Describe the solution you'd like
To have each of the following config items controllable with env vars:

• timezone
• format
• taskwait
• timeout

Describe alternatives you've considered
The $HOME/.acquiacli/acquiacli.yml still works for phar files but may not be good to use in distributed environments.