Install of the service fails to take account of a different user

[borpin]

The installation of this service fails to follow the convention of other services in the stack and check for the USER to be used.

e.g.

https://github.com/openenergymonitor/EmonScripts/blob/faf295b371d32868e1050dd2b202d8a9d397fcb3/install/emoncms_core.sh#L86

This results in a failed Ubuntu install.