added clear() method to the input class

Signed-off-by: Dayle Rees <thepunkfan@gmail.com>

laravel/documentation/input.md

@@ -145,4 +145,10 @@ Sometimes you may wish to merge or replace the current input. Here's how:
 
 #### Replacing the entire input array with new data:
 
-	Input::merge(array('doctor' => 'Bones', 'captain' => 'Kirk'));
+	Input::merge(array('doctor' => 'Bones', 'captain' => 'Kirk'));
+
+## Clearing Input
+
+To clear all input data for the current request, using the `clear()` method, for example:
+
+	Input::clear();