Update Mac OS X binary to v1.7.83
Update Mac OS X binary to v1.7.83

* built with libpng version 1.6.16
* compiled with gcc version 4.2.1 Compatible Apple LLVM 6.0
(clang-600.0.56)

source: http://sourceforge.net/projects/pmt/files/pngcrush/1.7.83/

imagemin/pngcrush-bin