CCWMP-19859: Add "webOSThemeChange" event

Related JIRA ticket - http://clm.lge.com/issue/browse/CCWMP-19859
We created a new webos event "webOSThemeChange" as in
http://clm.lge.com/issue/browse/CCWMP-18894. Please register this event in enyo-webos so that all enyo/garnet app's could get the notification when the "theme" (or, "font type" as of now) changes.

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Enyo-DCO-1.1-Signed-off-by: Seungho Park <seunghoh.park@lge.com>