Add ferox-config.toml to installation

[epi052]

closes #1

The current installation does not place the ferox-config.toml anywhere on the filesystem. The .deb places it in /etc/feroxbuster, as it's expected to be executed with root permissions.

My thought is to copy it into the config directory that the library used in feroxbuster points to on a mac (https://docs.rs/dirs/3.0.1/dirs/fn.config_dir.html).

I've already done similar with the linux version, and all seems to work as expected.

This is in response to, and closes, this issue.