Bump knife-spork version to 1.4.1

Bumps the included knife-spork version to 1.4.1, which includes the following newness and bugfixes:

1.4.0: https://github.com/jonlives/knife-spork/blob/master/CHANGELOG.md#140-21st-august-2014
1.4.1: https://github.com/jonlives/knife-spork/blob/master/CHANGELOG.md#141-21st-august-2014