Updated the edxapp Docker image to be based on Ubunut 16.04

docker/build/edxapp/Dockerfile

@@ -8,7 +8,7 @@
 # with the currently checked-out configuration repo.
 
 
-FROM edxops/precise-common:latest
+FROM edxops/xenial-common:latest
 MAINTAINER edxops
 USER root
 CMD ["/edx/app/supervisor/venvs/supervisor/bin/supervisord", "-n", "--configuration", "/edx/app/supervisor/supervisord.conf"]

playbooks/roles/edxapp/tasks/main.yml

@@ -118,7 +118,7 @@
   tags:
     - install
     - install:base
-    
+
 - name: install system packages on which LMS and CMS rely
   apt:
     name: "{{ item }}"
@@ -151,7 +151,7 @@
   tags:
     - install
     - install:base
- 
+
 # Set up the python sandbox execution environment
 - include: python_sandbox_env.yml
   when: EDXAPP_PYTHON_SANDBOX