**proof of concept**

[-] convert JSON to Objective-C object
	- support nested object mapping
	- support mapping array with custom class, not support nested array mapping
[-] convert Objective-C object to JSON

###############
json spec:
###############

object
    {}
    { members }

members
    pair
    pair, members

pair
    string : value

array
    []
    [ elements ]

elements
    value
    value, elements

value
    string
    number
    object
    array
    true
    false
    null

###############
Foundation spec:
###############

object(NSDictioanry)
    {}
    { members }

members
    pair
    pair, members

pair
    string : value

array(NSArray)
    []
    [ elements ]

elements
    value
    value, elements

value(id)
    NSString
    NSNumber
    NSNumber
    NSNumber
    NSNull
    object(NSDictionary)
    array(NSArray)

###############
object spec:
###############

object(CustomObject)
    { members }

members
    pair
    pair, members

pair(property)
    string(property_name) : value(property_value)


array(NSArray)
    []
    [ elements ]

elements
    value
    value, elements


value(id)
    NSString
    NSNumber
    NSNumber
    NSNumber
    NSNull
    array(NSArray)
    object(CustomClass)