[WIP] Use trollop option parsing for git reference instead of VERSION file

The VERSION file path as part of the nightly build scripts was not reliable.

Additionally, it feels ugly that the build code used to generate the kickstarts for the appliances needs to have access to the VERSION file from the desired branch/tag/reference.
Any by useful, not "reference is required"... that's basically why I changed it to be little nicer:

`
Error: argument --reference provide a git reference such as a branch or tag.
`