Gemfile: require Minitest 5
Gemfile: require Minitest 5

Before this commit:

* fresh bundle gets Minitest 5
* existing bundle still has Minitest 4.x and
  may fail due to minitest/autorun in spec_helper

After this commit:

* all bundles get Minitest 5

maxgaulhofer/puppet-chocolatey,maxgaulhofer/puppet-chocolatey,krutisfood/puppet-chocolatey,idoru78/puppet-chocolatey,ferventcoder/puppet-chocolatey,cregev/puppet-chocolatey,rismoney/puppet-chocolatey,chocolatey/puppet-chocolatey,idoru78/puppet-chocolatey,korytkoBT/puppet-chocolatey,cregev/puppet-chocolatey,9bryan/puppet-chocolatey,rismoney/puppet-chocolatey,ThoughtCrhyme/puppetlabs-chocolatey,9bryan/puppet-chocolatey,korytkoBT/puppet-chocolatey,ThoughtCrhyme/puppetlabs-chocolatey,chocolatey/puppet-chocolatey,ferventcoder/puppet-chocolatey