GCM-Key with own instance of OpenHAB-Cloud


I would like to use HABDroid with my own hosted OpenHAB-Cloud instance.
Is it possible to change the application, so that anyone could set the GCM-Key in an advanced (or hidden) option?
If no key is set, the default key for myOpenHAB could be used.

With this improvement, it will be unnecessary to compile my own HABDroid-Version only because I use my own cloud instance.