Updated the JSON encoder to be able to handle colander.null instances.
Updated the JSON encoder to be able to handle colander.null instances.

paasmaker/paasmaker,paasmaker/paasmaker,kaze/paasmaker,paasmaker/paasmaker,paasmaker/paasmaker,kaze/paasmaker,kaze/paasmaker,kaze/paasmaker,kaze/paasmaker,paasmaker/paasmaker