Don't use given/when

These give warnings in Perl >= 5.18:

  given is experimental at /home/hydra/src/hydra/src/lib/Hydra/Helper/CatalystUtils.pm line 241.
  when is experimental at /home/hydra/src/hydra/src/lib/Hydra/Helper/CatalystUtils.pm line 242.
  ...

src/script/hydra-evaluator

@@ -1,7 +1,6 @@
 #! /var/run/current-system/sw/bin/perl -w
 
 use strict;
-use feature 'switch';
 use utf8;
 use Hydra::Schema;
 use Hydra::Plugin;