Fix broken test due to overlapping sample interval
throw an exception if service is not declared properly
allow model-distance-calculations.json to be missing
Merge branch 'verify-service-declaration'
Merge branch 'master' into android-l-apis
Got old API 18 scan APIs working with new CycledLeScanner
Merge branch 'android-l-apis' of github.com:AltBeacon/android-beacon-library into android-l-apis

Conflicts:
	src/main/java/org/altbeacon/beacon/service/Stats.java
	src/test/java/org/altbeacon/beacon/service/StatsTest.java