use mDNS to access web UI with usb.nugg

[AlexLynd]

This feature uses multicast DNS to resolve the domain usb.nugg to 192.168.4.1 since its easier to remember.
Since the mDNS defaults to a .local domain, we use the DNSServer library to use a completely custom domain.

[brandonpaiz]

Super interested in using mDNS to make it easier for users to connect to the web interface 🙂

Quick note about the commit:

It's hard to review changes when styling/formatting changes are mixed in. Breaking this into a few commits would be helpful. I'm not convinced the style changes are necessary though, were they done automatically? Bracket placement is a touchy subject, but in general I'd say as long as we're consistent it's fine. Although the style guide prefers the old way:

The open curly brace is always on the end of the last line of the function declaration, not the start of the next line.

It suggests similar bracket placement for if/while/etc

Have you used git add -p <file> before? It makes it suuuuuper convenient to just stage part of a file (more here: https://nuclearsquid.com/writings/git-add/). Let me know if you want to pair up in a meeting to do git manipulation stuff.

[brandonpaiz]

Added the "enhancement" label, I'm thinking of using this label for features we want to talk about in the release notes :)

[pascal2313]

make it also that you can change it in the config file

[brandonpaiz]

Updated branch to revert formatting changes

[brandonpaiz]

@pascal2313

make it also that you can change it in the config file

Will consider for future release 👍