Add CLI version

[maltsev]

For now, I made it quite simple: the options can be passed only via the configuration file.

Later, we might add CLI args for the options.

The help section:

# ./dist/bin.js --help
Usage: htmlnano [options] [input]

Minify HTML with htmlnano

Arguments:
  input                  input file (default: "-")

Options:
  -o, --output <file>    output file (default: "-")
  -p, --preset <preset>  preset to use (default: "safe")
  -c, --config <file>    path to config file
  -h, --help             display help for command

It relies on #383 bug fix.

Original issue: #3