Additonal tests

[joshua-hampton]

Added a lot of tests, covering most of:

• cli.py
• cvs.py
• generic.py
• readers/cdl.py
• readers/image.py
• rules/processors.py
• rules/rule_funcs.py
• rules/rules.py
• specs.py
• utils.py

This also includes the addition of some test files, test vocabs, and test specs.

Writing these tests also showed a few small issues within the code that needed correcting. No new functionality has been added to checksit.

[joshua-hampton]

ncdump not found on the runner machine, will add installation of netcdf module to main workflow