[Runtime] Add Tizen Setting handler for widget application.

Add handler for Tizen setting element in Widget configuration, so
that we can parse and validate Tizen setting information.

This PR only supports 'hwkey' attribute at present, other attributes
e.g, 'background-support' will be added later when needed.
Merge pull request #1818 from shaochangbin/tizen-setting-handler

[Runtime] Add Tizen Setting handler for widget application.