Add info && change core

I made some quick tweaks to include the "Info" command, since it's not included in your original plan. I've also moved the "core" command to the "TRACE" level. 

I feel this more accurately matches the layout described on https://metacpan.org/module/Dancer::Cookbook#Configuring-logging (shows that CORE is lower level than DEBUG, instead of higher.", and the missing "INFO" level was causing me no end of trouble.

The tests have been updated to match.