Alternative Init #248

Introduction
Some systems such as Alpine Linux based distributions do not use systemd as the service manager(/everything-daemon).
This feature request is for support on these distributions.

Describe The Problem To Be Solved
Currently, Eruption will not compile without libsystemd0 available.

Describe the Solution
Allow Eruption to compile without systemd components, and possibly add support for other init systems in the future.
It's not necessary to go out of the way to support other init systems so long as Eruption can compile as a regular set of binaries that are not integrated with libsystemd. At that point other people can write the necessary init scripts and services to run said binaries.

I would just compile and use roccat-tools, but I have a Roccat Pyro keyboard, and only Eruption is working on supporting that model AFAIK.
I'll try to compile my own version of this and make the change an automatic configuration flag if I can, since that's generally good practice, but Rust isn't usually my cup of tea.