Upgrade Prometheus node exporter to Prometheus collection

Change-Id: I182c6114ee525090d2661bb0d48781e292d66919

prometheus/README.rst

@@ -25,7 +25,7 @@ Downloading role dependencies
 .. code-block:: bash
 
     cd /opt/openstack-ansible-ops/prometheus
-    ansible-galaxy install -r ansible-role-requirements.yml
+    ansible-galaxy install -r requirements.yml
 
 
 Install node_exporter

prometheus/ansible-role-requirements.yml

@@ -1,5 +0,0 @@
----
-- name: node-exporter
-  scm: git
-  src: https://github.com/cloudalchemy/ansible-node-exporter
-  version: master

prometheus/installNodeExporter.yml

@@ -12,9 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+- name: Refresh local facts
+  hosts: hosts
+  tasks:
+    - name: Refresh local facts
+      setup:
+
 - name: node_exporter
   hosts: hosts
   vars_files:
     - vars/variables.yml
   roles:
-    - role: node-exporter
+    - role: prometheus.prometheus.node_exporter

prometheus/requirements.yml

@@ -0,0 +1,6 @@
+---
+
+collections:
+- name: prometheus.prometheus
+  version: 0.8.0
+  type: galaxy