Fix tag parsing for `Name tag` in OpenStack Entities

Problem/Motivation

The code in OpenStackService::getTagName() parses the Name tag using the old convention.

For example:

      ["Tags"]=>
      array(2) {
        [0]=>
        string(55) "created_by_uid__di_openstack_regionone__b85098564701__1"
        [1]=>
        string(19) "Name__suzuki-test-2"
      }

In the updated convention, the Name tag is stored like this

      ["Tags"]=>
      array(2) {
        [0]=>
        string(51) "drupal-openstack.2b16ec6ef106d11805555d08624e2f47.1"
        [1]=>
        string(12) "Name.Baldwin"
      }

Update OpenStackService::getTagName() to parse using the "." instead of "__"