If no vagrant-proxyconf plugin installed, recommend installation (though it will work without)
Install vagrant-vbox-snapshot plugin if not present (enforce version)
Convert ENV constant to a hash
Corrected wrong argument
Merge pull request #709 from ppp0/issue-709

Make vagrant_helper portable, recommend plugin
Merge pull request #710 from ppp0/issue-710

Fix another regression (ENV merge)
Merge branch 'master' of github.com:cargomedia/puppet-packages into issue-688