Fixed code to work when body is empty

Now passes empty JSON data through the collection system to remove
errors about unknown keys when posting via other methods

flight/net/Request.php

@@ -187,9 +187,12 @@ class Request {
 
         if (strpos($this->type, 'application/json') === 0 && $this->body != '') {
             $this->json = json_decode($this->body, true);
-			$this->json = new Collection($this->json);
+        } else {
+            $this->json = array();
         }
 		
+        $this->json = new Collection($this->json);
+		
     }
 
     /**