Minor model changes
Merge branch 'master' of https://github.com/devicehive/devicehive-java

Conflicts:
	src/main/java/com/devicehive/model/Device.java
	src/main/java/com/devicehive/model/DeviceClass.java
SubscriptionsManager prototypes
Merge branch 'master' of https://github.com/devicehive/devicehive-java