IFTTT feature: add support for realtime API

[mauryquijada]

Lately, it seems like myopenHAB has been struggling with IFTTT polling overload. I looked into this, and according to IFTTT API documentation, this could be improved by the realtime API. This also has the benefit of making IFTTT updates more realtime. Also, there's been a 2 year old issue about this here: #116

[digitaldan]

Thanks so much for the contribution! I was actually chatting with @kaikreuzer about this API call and the fact we are not using it, but should be. As soon as i modify how we store our events i will look at your changes so we can incorporate them.

Just to be clear, our primary load issue is not IFTTT polling (well, at least not the main load problem) , the big issue is the Item and Event updates coming from peoples openHABs (whether they use IFTTT or not). I have a change to how these are stored that i hope will alleviate much of the issue, but I need to run it through some tests first.

[hmerk]

@digitaldan Same as before, or is IFTTT back ?