Added ability to change log level - default level set to Error

[thatcoderguy]

• Removed the "enable debug" option from config
• We now have 5 different logging levels which can be set
• Logging enabled by default, but set to Error (so nothing only exceptions are logged)
• The next PR will be me adding different more logging statements, but with the relevant logging level

[thatcoderguy]

Not a fan of where I've moved config.json check to in the code... another way of doing would be to set the default logging level to Debug, then just before the config file is read, change it to Error, then change it again when we know what the config file says.