set puppet version to approximation

This commit sets the version of puppet to install
as the approximate version to by adding ~> to the version
string.

Previously, the version number was not valid.

Change-Id: I3cf70986f951049f6f5f5d49a54629b7e29152c0
Reviewed-on: https://review.openstack.org/26401
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins