Ensure we check json_route before using it

Fixes #336

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2149 f69abe3c-2ee2-4550-9a6d-17bd458115be
Conditionally load classes

This may affect performance. Fixes #337

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2150 f69abe3c-2ee2-4550-9a6d-17bd458115be