update for Update jsb_basic_conversions.mm

fixed rounding bug in JSB_jsval_from_NSNumber
this bug results in a wrong number in js
1.4 (native) -> 1.400000024556 (js)

JSB_jsval_to_NSSet now uses a real NSSet

in JSB_jsval_to_NSDictionary the key can be a number or a string
-> now JSB_jsval_from_NSDictionary also