Change the API.

Change the API.

1. Reduce the set of API.
2. Progressive Disclosure (PD) is changed to Glance Bar (GBAR).
3. DBOX_STATUS_SUCCESS is replaced with DBOX_STATUS_ERROR_NONE.
4. Remove privlevel if it doesn't required
5. Add @internal tag to all API. because this module doesn't want to be exposured to 3rd party developer
6. Change the privilege URL to tizen.org/privilege/dynamicbox.viewer
7. Add more status of return value
8. ERROR_INVALID -> ERROR_INVALID_PARAMETER,
   ERROR_MEMORY -> ERROR_OUT_OF_MEMORY
9. ERROR_IO -> ERROR_IO_ERROR
10. ERROR_PERMISSION -> ERROR_PERMISSION_DENIED
11. Replace documentation file name livebox-viewer_doc.h with dyanmicbox_viewer_doc.h

Change-Id: I75ec760a88f4a71a24f0124941260bacac0e7427