Preventing large ints being converted to floats when decoding.

Integers larger than PHP_INT_MAX are getting automatically converted into floats by the json_decode() call. This is a problem if those ints are intended to be used as entity IDs.

This fix automatically converts large integers in JSON into strings instead, using the JSON_BIGINT_AS_STRING option param for PHP versions that support it (>=5.4.0), or in older versions by preprocessing the JSON string with preg_replace() to add quote marks around any integers longer than strlen((string) PHP_INT_MAX) - 1.
Why is the assoc parameter here `true` when the default and version above are `false`?