Do not send map for simple-push on broadcast

This line is wrong:

https://github.com/aerogear/aerogear-push-quickstart-backend/blob/master/src/main/java/org/jboss/aerogear/aerodoc/service/LeadSender.java#L63

In:
https://github.com/aerogear/aerogear-push-quickstart-backend/blob/master/src/main/java/org/jboss/aerogear/aerodoc/service/LeadSender.java#L71

We need to send a simple string there, like:

json.put("simple-push",  "version=" + broadcastVersion++);

the message spec does not state that 'broadcast' needs to be identified, this is something that our UnifiedPush server and our SimplePush server do, implicit.