fix(nutcracker.spec): Fails to build on RHEL 6

Running "rpmbuild -ba nutcracker.spec" on RHEL 6 fails with:
error: bad date in %changelog: Tue July 30 2013 Tait Clarridge <tait@clarridge.ca>
Merge pull request #190 from oremj/fix_spec_changelog

fix(nutcracker.spec): Fails to build on RHEL 6