Porter Air Gap Installation

[sgettys]

Is your feature request related to a problem? Please describe.
The execution of Porter should have a fully supported air gap solution so that porter itself doesn't attempt to pull in external images when running in an air gap (ex: Mongo image for config backend)

Describe the solution you'd like
The first porter execution should not attempt to pull down the mongo docker image when running across an air gap. We should provide an easy mechanism to package up the porter CLI and the mongo image for running the local porter state and send across an air gap.