Merge pull request #4758 from butane/uri_scheme_case

URI schemes are not case-sensitive
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 25dc0d4..61f0298 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -1200,7 +1200,7 @@
 			{
 				return FALSE;
 			}
-			elseif ( ! in_array($matches[1], array('http', 'https'), TRUE))
+			elseif ( ! in_array(strtolower($matches[1]), array('http', 'https'), TRUE))
 			{
 				return FALSE;
 			}