Bump version. Minor syntax update.

VERSION

@@ -1 +1 @@
-1.2.9
+1.2.10

flight/net/Response.php

@@ -237,7 +237,7 @@ class Response {
 
         // Send content length
         if (($length = strlen($this->body)) > 0) {
-            header("Content-Length: $length");
+            header('Content-Length: '.$length);
         }
 
         return $this;