Add a new prometheus metric to track which jails are currently enabled.
Add a new database query to read the jail name and enabled status from the
database.
Add new metric to readme file.
Update the project structure to move all golang files to a new `src/`
folder. This keeps all the code located in the same place and easier to
work with.
Update the Makefile and goreleaser config to continue to work with the new
folder structure.