Display "keys available" JSON for saving

All inputs how have valueUpdate: 'keyup' bindings
Override how ko.mapping.toJSON works to gain indentation support
Signature of init changed to init(overrides, parent, defaults)
This allows the mapping plugin to keep track of all properties without
having to use a ridiculously huge "include" argument
Added function createInitArgs to assist with changes made to init
Refactored all constructors to use the new init() mechanism