Update of DRM framework

 - Overload openDecryptSession() with uri parameter
   in order to accept URI of DRM content,
   Following API is added,
       DecryptHandle*openDecryptSession(const char* uri);.
 - Unify texisting three event types of processDrmInfo()
   so that caller of DRM framework does not have to handle many event types.
 - Let DrmManagerService call load/unload plugins API so that
   client of DRM framework does not have to manage plug-in load/unload.
 - Trivial fix in DrmManagerClient.java is also incorporated.

Changes are made by Sony Corporation.

Change-Id: If62b47fa0360718fdc943e6e6143671d7db26adc