Bug 959011 - Decline call with message

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Since these _onQuickReplyActivity/event handler/... simply belongs to this quick reply behavior, it would be great and cleaner to move these function into a module within another js file like what we do for thread_ui.js/thread_list_ui.js . 

We use navigation.js for view show/hide now in message app, so please use these api to manage the view instead of accessing the Dom element directly.