Add nginx roles to plays and add new plays.

Added new plays for splunkforwarder and datadog and added
nginx to the xqueue, xserver, and edxapp plays.

playbooks/edx-east/datadog.yml

+- name: Deploy datadog
+  hosts: all
+  sudo: True
+  gather_facts: True
+  vars_files:
+    - ["{{ secure_vars }}", "dummy.yml"]
+  roles:
+    - datadog
+

playbooks/edx-east/edxapp.yml

@@ -5,4 +5,9 @@
   vars_files:
     - ["{{ secure_vars }}", "dummy.yml"]
   roles:
+    - role: nginx
+      nginx_sites:
+        - lms
+        - cms
+        - lms-preview
     - edxapp

playbooks/edx-east/splunkforwarder.yml

+- name: Deploy the splunkforwarder
+  hosts: all
+  sudo: True
+  gather_facts: True
+  vars_files:
+    - ["{{ secure_vars }}", "dummy.yml"]
+  roles:
+    - splunkforwarder
+

playbooks/edx-east/xqueue.yml

@@ -5,4 +5,7 @@
   vars_files:
     - ["{{ secure_vars }}", "dummy.yml"]
   roles:
+    - role: nginx
+      nginx_sites:
+      - xqueue
     - role: xqueue

playbooks/edx-east/xserver.yml

@@ -5,4 +5,7 @@
   vars_files:
     - ["{{ secure_vars }}", "dummy.yml"]
   roles:
+    - role: nginx
+      nginx_sites:
+      - xserver
     - role: xserver