Set up Config.json & Model(s) selection & Click for parse options

[Noppapon]

Addressing initial discussions and comments in #1

• Combine UPDATE_CHECK_FILE and USERID_FILE into one config.json
• Allow user to preset Gorilla to use only some models through --set_models <models file path>
• Allow user to choose a model on the go (override the config), -m or --model
• Minor code refactoring

Further enhancement

• Use Click for better UI argument parsing