Jibsheet/use configuration source checking

Simple playbook to take security updates on hosts

add security upgrade flag to te jenkins plays

* fix the analyticstack box (#3369)

* revert change to vagrant version

Use unattended-upgrade to only take security updates

This allows for security updates to be applied during artifact creation,
but not applying other updates.

Add a new check which allows checking for extra config

Adding PUBLISHER_FROM_EMAIL for sending emails.

We include configuration from multiple sources, and we wanted a way
to ensure that a list of variables (canaries) have been defined
in our various configuration override repos and then -e@'ed in.

remove updates available check from MOTD

install pysqlite for devstack and jenkins workers

adding symlink pointing to 2.6

ECOM-6141

AN-7716 Update grading policy api url to new api

Add trailing slash to run_migrations so files go in to a directory

ECOM-2979

Added new setting variable "EXPIRING_SOON_WINDOW: 28"

ECOM-5847 ( Adding email functionality in DISCOVERY IDA )

Reorder AMI names so they sort better in the console

Jibsheet/disable automated upgrade 16.04

Backport fixes from e0d/xenial that enable the automated dockerfile

Update the configuration for the non-ses email backends.

ECOM-5847

Fix typo in yarn-site.xml template.

instruct nginx to add a X-Queue-Start header

This header gets added to requests proxied by nginx to various edx apps.
The New Relic agent, if there is one, reads this header to calculate the
time each request spends between the web server (nginx) and the
application server (django or some other cms).

The specific intention of this commit is to measure the time requests
spend queued at the gunicorn layer.