Altered Duplicated code between repos

[WilliamMcCumstie]

The appliance_cli code has been duplicated across various repos:
https://github.com/alces-software/userware
https://github.com/alces-software/imageware

This is going to start to cause maintainability issues and should be created into a shared library. To complicate the issue, the code base has changed slightly in adminware. The PR responsible for the change will be linked to this issue.

[WilliamMcCumstie]

We should also do this TODO:

adminware/src/appliance_cli/command_generation.py

Line 122 in d0149e7

# TODO Could create Argument and Arguments classes as with Options; don't