RFM2Pi Gateway: Bug in emonglcd time send

Apparently there's a bug in my implementation.

This pull request is meant to solve this: https://github.com/emoncms/raspberrypi/issues/34

Fix provided by Denis here: https://github.com/Jerome-github/oem_gateway/issues/3

Fix included in OEM Gateway (standalone) here: https://github.com/Jerome-github/oem_gateway/commit/43eb3c6d51242c9c6795f4cfca35dbc189db8292

I can't test and I dont know why it should be this way or another, but this is the way it is done in the php gateway and it was tested by Denis.