Maxcul binding initial implementation (#1085)

This is an initial pull request for the Max!CUL binding implementation as per #1085.

Currently it has the ability (tested) to pair a radiator thermostat and wall thermostat unit. 

Wall thermostat units have bi-directional communication (i.e. desired temperature can be set from OpenHAB and openhab will update the unit and vice versa).

For radiator thermostat units you can only set the desired temperature from openhab, not from thermostat to openhab. Hopefully this will be done next as well as starting a wiki page :)
The reason I use this method is that the information stored (device radio address) in this file isn't available until the user goes through the Max! pairing process with the binding. There is no other way (unless the user has a Max! Cube) to extract the device's radio address - hence why it can't be in either the binding config or openhab.cfg.

I hope that makes sense.

Thanks,
Paul