minor #4376 Cleaned up javascript code (flip111)

This PR was squashed before being merged into the 2.3 branch (closes #4376).

Discussion
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Cleaned up javascript code

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets | n/a

1. Reused variable `emailList` which is best practice and easier to read
2. Removed `return false`. There is no use for it in this context and many consider it to be bad use as well. For example: http://fuelyourcoding.com/jquery-events-stop-misusing-return-false/

Commits
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8931249 Cleaned up javascript code

reference/forms/types/collection.rst

@@ -179,7 +179,9 @@ you need is the JavaScript:
             var emailCount = '{{ form.emails|length }}';
 
             jQuery(document).ready(function() {
-                jQuery('#add-another-email').click(function() {
+                jQuery('#add-another-email').click(function(e) {
+                    e.preventDefault();
+
                     var emailList = jQuery('#email-fields-list');
 
                     // grab the prototype template
@@ -192,9 +194,7 @@ you need is the JavaScript:
 
                     // create a new list element and add it to the list
                     var newLi = jQuery('<li></li>').html(newWidget);
-                    newLi.appendTo(jQuery('#email-fields-list'));
-
-                    return false;
+                    newLi.appendTo(emailList);
                 });
             })
         </script>