[Tizen][Linux] Support the following URI schemes: tel://, sms://, mailto://.

Override content::RuntimeResourceDispatcherHostDelegate::HandleExternalProtocol
to implement the platform-specific surpporting:

1 On TizenIVI, through DBus to invoke corresponding default system application.
2 On Linux, use XDG utils.
3 On Android, it's been implemented already, keep unchanged.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1501