Allowed to use repository scripts from overlay one & some bug fixes

This change allows organization to override, track & store own changes while using the bait framework & images as much as possible.

Now it supports running custom specs, bait specs, custom ansible override.yml roles & playbooks for sure. Also pack, check style & upload scripts. Just follow the readme documentation Overlay repository to setup the overlay repo properly.

Also fixes some found style & other issues.

Related Issue

fixes: #25

Motivation and Context

This one was a long one - previously I stored the override.yml & specs in the same bait repo untracked - but enough this nonsense now we can safely track the overlay changes.

How Has This Been Tested?

Manually - aws, vmx & native images from overlay repo & from bait repo.

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[x] I have signed the Adobe Open Source CLA.
[x] My code follows the code style of this project.
[x] My change requires a change to the documentation.
[x] I have updated the documentation accordingly.
[x] I have read the CONTRIBUTING document.
[ ] I have added tests to cover my changes.
[x] All new and existing tests passed.

adobe / aquarium-bait