docs: add the ability to exclude PRE elements from being prettified

by adding the class "no-pretty-print" (needs to hyphenate 'prettyprint',
otherwise the prettify script will parse "no-prettyprint" the same as
"prettyprint")

tools/droiddoc/templates/assets/android-developer-docs.js

@@ -64,7 +64,7 @@ addLoadEvent( function() {
 } );
 
 addLoadEvent( function() {
-  $("pre").addClass("prettyprint");
+  $("pre:not(.no-pretty-print)").addClass("prettyprint");
   prettyPrint();
 } );