Implement delegate callback for navigation decision on default livebox plugin

Implement delegate callback for navigation decision on default livebox plugin

[Issue#] N/A
[Problem] There is no interface that handles 'box' scheme on livebox plugin
          This interface is needed for AppWidget Web API to be used by Box and PD content of default livebox
[Cause] This interface is not considered by now, because requirement of AppWidget Web API is newly added.
[Solution] wrt delegate callback for this is added, this callback is implemented in default livebox plugin.
[SCMRequest] This patch is dependancy to the following patch of 'wrt' package
             https://tizendev.org/gerrit/#/c/64349/

Change-Id: I2b6eb845d17464d199c551d7ecc313dbd29b8536