Warning: I am sure this is a very noob question. I take no responsibility for side splitting laughter at my naivety. 

I would like to be able to open and close my garage door with my phone (I have a perfectly good remote, but that's not the point). Having trawled the internet for pretty basic information, I think I should be able to do this with a simple relay switch. One option might be an Arduino stacked with ethernet and relay shields, but I have a strong feeling that there is probably a simpler way than this.

The garage door (the very common Merlin 430R) has a couple of ports for attaching a hard wired switch. This seems to work along the lines of 

 if circuit closed, then activate door 

I've tested this (perhaps foolishly but it works) by closing the circuit with a length of wire and indeed I can control the door just by closing the circuit. The door knows whether it's open or closed and so just does the opposite. If it's currently moving and the circuit is closed, the door will stop.

So I think all I need to do is wire in a relay between the manual control ports. However, my query is whether there is a simple single board module that I could make work with this? I have a vague notion of using openHAB on a Raspberry Pi as the controller (and then from that to my phone), but am pretty open to other controller options if that would be best.

I have seen some commercial offerings (MyQ, Garageio) but these all seem to anticipate more a tilt style door that you can attach additional sensors to. There are also a couple of bluetooth options that I can fall back to if necessary, but ideally I'd like to be able to control the door completely remotely.

As an addon, I'd like to add some kind of proximity sensor so I can tell remotely whether the door is open or closed. But that's probably a second stage project.

Any advice about the relay board options?