Add clap as a CLI argument parser and add debug flag to change log level

[jannikac]

Hi,
I took a look at you code and thought why not use a pre-made CLI parsing library like clap to parse the CLI arguments instead of doing it manually. This also automatically generates a help menu with --help or -h and by deriving version also prints the programs version when --version or -V` is passed.

I've also added a --debug or -d flag which enables debug logging and therefore changes the default log level to info because I think a regular user would be fine with logging just the info messages and adding more logging when they so desire.

I thought this would be useful as a base to later implement more CLI args like changing the config file location.

[haimgel]

👏 (pun intended), thank you!