Move mikey179/vfsStream to only be required on dev
diff --git a/composer.json b/composer.json
index c13ac5a..bf3b3d2 100644
--- a/composer.json
+++ b/composer.json
@@ -2,9 +2,9 @@
     "name" : "ellislab/codeigniter",
     "require": {
         "php": ">=5.2.4",
-        "mikey179/vfsStream": "*"
     },
     "require-dev": {
+      "mikey179/vfsStream": "*"
 		  "phpunit/phpunit": "*"
 		}
 }
\ No newline at end of file