Revert font awesome 5 changes

We are still pushing ahead on this 100% just need a bit longer to prepare
all plugins

plugins/poll/assets/javascripts/initializers/add-poll-ui-builder.js.es6

@@ -32,7 +32,7 @@ function initializePollUIBuilder(api) {
   api.addToolbarPopupMenuOptionsCallback(function() {
     return {
       action: "showPollBuilder",
-      icon: "chart-bar",
+      icon: "bar-chart-o",
       label: "poll.ui_builder.title",
       condition: "canBuildPoll"
     };