break up logging functions when using systemctl?

[spencersevilla]

Currently the HSS, MME, and SPGW all output to one journalctl each. Each log is about 99% function calls/traces and 1% useful information. Keeping the traces is a good idea for debugging (i.e. something crashes and we want to know what happened) but I'd love to see them stored in a separate journalctl, so that typing journalctl {hss|mme|spgw} gives you cleaner/saner/readable output, and you only have to check the other journalctl for debugging.