URI base tag look up optimization

- base tag doesn't need to be extended
- uses compatible and more lightweight document.getElements
- Indirectly fixes ticket #72

Source/Native/URI.js

@@ -140,7 +140,7 @@ URI.regs = {
 	directoryDot: /\.\/|\.$/
 };
 
-URI.base = new URI($$('base[href]').getLast(), { base: document.location });
+URI.base = new URI(document.getElements('base[href]', true).getLast(), { base: document.location });
 
 String.implement({