The `up` metric is now based on whether an error was found while reading
data from the database to build other metrics. Note that there is a chance
the `up` metric will not be correctly set if the last metric to be built
before the `up` metric does not throw an error.
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.
