Added the ability to dynamically generate a Nestable list passing in
serialized JSON (in the same format as the serialize() JSON output)
* added a sanity check for default options (was throwing errors)
* contentClass attribute for dealing w/ custom item content
* added internal _build() if 'json' passed in the options
* serialize() will look for contentClass to add 'content' property
Merge pull request #9 from lhl/master

Added the ability to dynamically generate a Nestable list passing in serialized JSON (in the same format as the serialize() JSON output)