Normalize views' template fetching pattern

Typically, a view can specify its templateName and then use the default
render method on Whisper.View, except in some special cases like message
view or message detail where other operations are performed during
render.

// FREEBIE

js/views/phone-input-view.js

@@ -8,7 +8,7 @@
     Whisper.PhoneInputView = Whisper.View.extend({
         tagName: 'div',
         className: 'phone-input',
-        template: $('#phone-number').html(),
+        templateName: 'phone-number',
         render: function() {
             this.$el.html($(Mustache.render(this.template)));
             this.$('input.number').intlTelInput();