Require >=3 chars for datatable search

Performing a search with < 3 chars is not generally fruitful

app/assets/javascripts/osem-datatables.js

@@ -8,4 +8,25 @@ $(function () {
 
   $('.datatable:not([data-source])').DataTable();
 
+  $('.datatable').on('init.dt', function (e, settings, json) {
+    var datatableApi = $(this).dataTable().api();
+    // Thanks to cale_b:        https://stackoverflow.com/u/870729
+    // Stack Overflow question: https://stackoverflow.com/q/5548893
+    // Stack Overflow answer:   https://stackoverflow.com/a/23897722
+    // Grab the datatables input box and alter how it is bound to events
+    $(".dataTables_filter input")
+      .unbind() // Unbind previous default bindings
+      .bind("input", function(e) { // Bind our desired behavior
+        // If the length is 3 or more characters, or the user pressed ENTER, search
+        if(this.value.length >= 3 || e.keyCode == 13) {
+          // Call the API search function
+          datatableApi.search(this.value).draw();
+        }
+        // Ensure we clear the search if they backspace far enough
+        if(this.value == "") {
+          datatableApi.search("").draw();
+        }
+        return;
+      });
+  });
 });