[zen-49] Correct import statements across framework

- Ran a script that would create multiple import statements out of multi-line
  import statements, and which would sort all import statements in alphabetic
  order. Script is at https://gist.github.com/3079222 and was run by dropping
  into the library/Zend folder and typing (in zsh)
  "for file in **/*.php;do php /path/to/replace-uses.php $file; done"

src/NodeList.php

@@ -10,12 +10,12 @@
 
 namespace Zend\Dom;
 
-use Iterator;
 use Countable;
 use DOMDocument;
+use DOMElement;
 use DOMNodeList;
 use DOMXPath;
-use DOMElement;
+use Iterator;
 
 /**
  * Nodelist for DOM XPath query