Merge pull request #455 from edx/jarv/create-user

add create_user play

playbooks/edx-east/create_user.yml

+# Creates a single user on a server
+# Example: ansible-playbook -i "jarv.m.sandbox.edx.org,"  ./create_user.yml -e "user=jarv"
+- name: Create a single user
+  hosts: all
+  sudo: True
+  gather_facts: False
+  pre_tasks:
+    - fail: msg="You must pass a user into this play"
+      when: not user
+    - set_fact:
+        gh_users:
+          - "{{ user }}"
+  roles:
+    - gh_users