Promisify ddev-shell wrapper and use -j flag

[andrew-c-tran]

What happened (or feature request):

What you expected to happen:

ddev-shell wrapper currently does not use promises nor the -j flag in all calls. To ensure consistency of the wrapper and through the entire application, we should be returning a promise and JSON output for all calls.

How to reproduce this:

note that list, describe and hostname in ddev-shell return promises and use the -j flag, but the older start/stop/restart calls do not.

Version: Please include the output of ddev version, docker version and the project's .ddev/config.yaml.

N/A

Anything else do we need to know:

N/A

Please use a complexity rating of 1-5 (5 is high) for a feature request. (High complexity implies more PR planning)

1