[Application] Add current application exit/hide support

The supported APIs are listed below:
Application.hide/exit

The implementation leverages running application object exported by the runtime
process on the DBus session. The "Terminate" and "Exit" methods of it only
permit the launcher process to access.

Supplement Application example for new added APIs are also added.
Merge pull request #289 from seanlong/app_dev

[Application] Add current app exit/hide support