fix: Some small UI tweaks

This will make the navbar look better on higher resolution screen.

feat: Add option to change feed's metadata

fix: Handle not found better (or at all)

By default go tunnels every request to "/", so I'd need to check for
paths at the podcast handler so I can report not found for anything
other than "/"

feat: Add view to select series

feat: Add more series

fix: Fix makefile

feat: Add metrics

feat: Rewrite to golang

I have found a nice lib in go to handle XML so I migrate to it.
Go is ages easier to deploy then python.

fix: Update url

fix: Add .gitignore to keep git clean