Merge pull request #687 from bluefuton/develop

Added HTTP status code 422 (Unprocessable Entity) to set_status_header()
diff --git a/system/core/Common.php b/system/core/Common.php
index e43bb8d..b0921fe 100644
--- a/system/core/Common.php
+++ b/system/core/Common.php
@@ -419,6 +419,7 @@
 							415	=> 'Unsupported Media Type',
 							416	=> 'Requested Range Not Satisfiable',
 							417	=> 'Expectation Failed',
+							422	=> 'Unprocessable Entity',
 
 							500	=> 'Internal Server Error',
 							501	=> 'Not Implemented',