HomeScreen-Service improvement

From two sides improving homescreen-service

• Improve class cohesion and reduce public interface number:
  # HS_ClientManager: only manager all clients and watch over connected session, don't concern request
  # HS_Client: deal with all request
  # In HS_ClientManager,delete interface functions who have the same name as verbs, added handleRequest function
  # 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:

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).

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