Fix systemd services.

Systemd services should be created at /lib/systemd/system instead of
/etc/systemd/system, once the service is enabled systemd will create a
link from /lib/systemd... to /etc/systemd...

Also systemd services should contain the absolute path to the executables.

Change-Id: I741fe249de8ecc7b2af100ca6cf55c51f86f84b0