Add systemd wrapper

OpenRC compatibility layer:
- Sets up the environment
- Sources the conf file
- Relays start, stop and restart command to the runscript
Refactor common functionality needed by net.lo

function.sh ensures that net.lo remains agnostic to the init system
- Helper functions like ebegin, einfo, etc are ensured
- Functionality like finding IFACE is handled by a function that
  appropriately handles various cases
Source functions.sh
Make calls to  from sh/functions.sh