Contain the versionlock subclass to help with ordering around package resources

[bovy89]

Fixes #43

[alexjfisher]

I think this causes dependency cycles when using versionlock in more than one profile where the role orders those profiles.

eg.

class profile::foo {
  yum::versionlock { '0:bash-4.1.2-9.el6_2.*':}
}

class profile::bar {
  yum::versionlock { '2:vim-enhanced-7.4.629-6.el7.x86_64':}
}

include profile::foo
include profile::bar

Class['profile::foo'] -> Class['profile::bar']

fails with

Error: Found 1 dependency cycle:
(Augeas[yum.conf_plugins] => Yum::Config[plugins] => Yum::Plugin[versionlock] => Class[Yum::Plugin::Versionlock] => Yum::Versionlock[0:bash-4.1.2-9.el6_2.*] => Class[Profile::Foo] => Class[Profile::Bar] => Yum::Versionlock[2:vim-enhanced-7.4.629-6.el7.x86_64] => Class[Yum::Plugin::Versionlock] => Yum::Plugin[versionlock] => Package[yum-plugin-versionlock] => Yum::Plugin[versionlock])\nTry the '--graph' option and opening the resulting '.dot' file in OmniGraffle or GraphViz
Error: Failed to apply catalog: One or more resource dependency cycles detected in graph