From two sides improving homescreen-service

• Improve class cohesion and reduce public interface number:

1. HS_ClientManager: only manager all clients and watch over connected session, don't concern request
2. HS_Client: deal with all request
3. In HS_ClientManager,delete interface functions who have the same name as verbs, added handleRequest function
4. In HS_Client,change interface function liked "showWindow" to private, added handleRequest function

Upper contents only need to change homescreen-service,don't influence other parts.

• Unified event pattern(except on_screen_message/on_screen_reply)
  Now in homescreen-service, the pattern of event as below:

{
  "application_id": "application id", //destination application's id,must be specified
  "type":"event name",   // must be specified
  "parameter":{"the specific contents to applilcation"}  // maybe null
}

But in hideWindow/showInformation/showNotification event application_id havs different meaning.For example, in hideWindow event application_id's meaning was the caller application's id.
This change related to homescreen-service and homescreen(related to notification).

sourcecode