Update to 3.5.3:

* Fix lower bound checking in scan_once / raw_decode API
https://github.com/simplejson/simplejson/issues/98
* Consistently reject int_as_string_bitcount settings that are not
positive integers
* Added int_as_string_bitcount encoder option
https://github.com/simplejson/pull/96
* Fixed potential crash when encoder created with incorrect options
* Native setuptools support re-introduced
https://github.com/simplejson/simplejson/pull/92