Fixes  Class::MOP::load_class deprecation warning

Hey,

This pull request fixes the Class::MOP::load_class deprecation warning.

Here's a blurb the Moose folks were distributing:

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We recently deprecated Class::MOP::load_class in Moose. It appears that your module is affected. You can read more about the change here: https://metacpan.org/pod/release/ETHER/Moose-2.1106-TRIAL/lib/Moose/Manual/Delta.pod#pod2.1200 We recommend that you take a look at your code to see if it indeed does need to be updated with respect to the latest Moose release, 2.1106-TRIAL. If you have any questions, then please ask either on Moose mailing list : http://lists.perl.org/list/moose.html or on #moose & #moose-dev on irc.perl.org.