Update Bootstrap to v4.1, fix chosen.js and pagedown on multiple sites

app/assets/javascripts/pagedown/pagedown.js.erb

@@ -0,0 +1,43 @@
+//= require markdown.converter
+//  markdown.editor is slightly adjusted to work with Bootstrap 4.
+//  Taken from https://github.com/hughevans/pagedown-bootstrap-rails, V2.1.4
+//= require markdown.editor
+//= require markdown.sanitizer
+//= require markdown.extra
+
+renderPagedown = function() {
+    $(".wmd-output").each(function (i) {
+        const converter = new Markdown.Converter();
+        const content = $(this).html();
+        return $(this).html(converter.makeHtml(content));
+    })
+};
+
+createPagedownEditor = function( selector, context ) {
+    if (context == null) { context = 'body'; }
+    return $(selector, context).each(function(i, input) {
+        if ($(input).data('is_rendered')) {
+            return;
+        }
+        const attr = $(input).attr('id').split('wmd-input')[1];
+        const converter = new Markdown.Converter();
+        Markdown.Extra.init(converter);
+        const help = {
+            handler() {
+                window.open('http://daringfireball.net/projects/markdown/syntax');
+                return false;
+            },
+            title: "<%= I18n.t('components.markdown_editor.help', default: 'Markdown Editing Help') %>"
+        };
+
+        const editor = new Markdown.Editor(converter, attr, help);
+        editor.run();
+        $('[data-toggle="tooltip"]').tooltip();
+        return $(input).data('is_rendered', true);
+    });
+};
+
+$(document).on('turbolinks:load', function() {
+    renderPagedown();
+    return createPagedownEditor('.wmd-input');
+});