Support app's with Dockerfile's

[jasonmccallister]

Description

Adding support for app.Dockerfile = true.

To Do

• Update apply logic
• Update the Nitro API to inspect the containers ports and apply routing automatically
• Update ssh to inspect the docker image
• Look at way to "build" during nitro apply and determine if the app image is out of date, possibly nitro apply --build?
• Disable features that we can't support with custom images

Related issues

• Support custom Dockerfile for site containers #344