kill the recursively spawning background thread. (it probably worked to keep the app alive in iOS6, but no longer works in iOS7)
refactor AppDelegate to record user preferences on app start/background/terminate
refactor periodically updating probes to pull config info from config.json
don't include ActivityManagerProbe in `[OpenSense availableProbes] if the phone doesn't support m7
notes:
* I'm starting to shift my efforts to UX design and creating an openPDS connector, so the probe-specific pulls may slow down now. (There are likely to be more integration pull requests)
* I think that the OSActivityManagerProbe is bug-free, but I don't have an iPhone 5S+ phone to fully test it with. Until I get my hands on one, it may remain untested.
* the periodic update probes _could_ inherit from a superclass, but there are only 3 of them... and the additional complexity of managing that just wasn't worth the very minor amount of DRYness that would have resulted
* there's still potential to wake-up the probes on significant location change. I'm leaving this for another time.
`[OpenSense availableProbes]if the phone doesn't support m7