Exposed statistical information about app launches and crashes via KSCrashAdvanced.

Also added application stats to the Apple crash reports, which look something like this:

	Application Stats:
	{
	    "active_time_since_last_crash": 7.66881,
	    "active_time_since_launch": 7.66881,
	    "application_active": true,
	    "application_in_foreground": true,
	    "background_time_since_last_crash": 4.17254,
	    "background_time_since_launch": 4.17254,
	    "launches_since_last_crash": 3,
	    "sessions_since_last_crash": 5,
	    "sessions_since_launch": 3
	}

Where:

- Session means a transition to foreground state.
- Time is measured in seconds.

Review:
- [x] @JaviSoto 
- [ ] @NachoSoto