Support sourcing deployment ENVs from config file

[jranson]

This contribution provides the ability to include and source ENVs in a config file as follows:

deployment:
  env:
    - ENV1=VALUE1
    - ENV2=VALUE2

It was also determined that addtiional-container-ports was not properly parsing from a config file; this is also fixed.

deployment:
  additional-container-ports:
    - debug:4000/tcp
    - label2:4001/udp

Lastly, it also includes some general cleanup of vars and repetitive raw strings that should be consts.