Update stdlib dependency to 4.x
Update stdlib dependency to 4.x

puppetlabs/stdlib 4.x is backwards compatible with 3.x and still tested
on Puppet 2.7. Updating stdlib to 4.x allows modules to use newer
functions without breaking older functionality.

Change-Id: Iaaac5678cdd00db3a03eb1f715e6cd91a25cefc8

JioCloud/puppet-openstacklib,gwdg/puppet-openstacklib