added not equals operator

Author: matthenning

src/Matthenning/EloquentApiFilter/EloquentApiFilter.php

@@ -309,6 +309,7 @@ private function getFilterOperator($filter)
         $operator = str_replace('lt', '<', $operator);
         $operator = str_replace('le', '<=', $operator);
         $operator = str_replace('eq', '=', $operator);
+        $operator = str_replace('ne', '!=', $operator);
 
         return $operator;
     }