allow ui-sortable options to be passed into the directive via sortOptions key on the form

Author: Chris Cornwell

src/array.html

@@ -2,7 +2,7 @@
       sf-field-model="sf-new-array"
       sf-new-array>
   <label class="control-label" ng-show="showTitle()">{{ form.title }}</label>
-  <ol class="list-group" ui-sortable>
+  <ol class="list-group" ui-sortable="{{form.sortOptions}}">
     <li class="list-group-item {{form.fieldHtmlClass}}"
         schema-form-array-items
         sf-field-model="ng-repeat"