Fix role gate tests for Ansible 2.3

Add 'become' and root 'user' options to the playbook instead of using
'ansible_become' through an inventory variable.

Change-Id: I5e703e24fe0b3aed2784fbf63d0f2e8f81d44f0b

tests/host_vars/localhost.yml

@@ -13,6 +13,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-ansible_become: True
 ansible_host: 127.0.0.1
 ansible_python_interpreter: "/usr/bin/python2"

tests/inventory

@@ -1,5 +1,5 @@
 [all]
-localhost ansible_connection=local ansible_become=True
+localhost
 
 [all_containers]
 

tests/test.yml

@@ -16,6 +16,8 @@
 - name: Playbook for role testing
   hosts: localhost
   connection: local
+  user: root
+  become: true
   roles:
     - role: "memcached_server"
   post_tasks: