feature: enhance test.py to ease testing and safe credential passing via file or cmd line args

[mike-dubman]

• add CLI + c4.properties file support for externalizing ip/username/password passing
• add help option to print supported cmd line options
• add device listing option;
• update .gitignore to ignore c4.properties file with credentials
• preserve existing testing line as comments

[mike-dubman]

@lawtancool plz consider