Add playbook for managing edxapp users

Null API keys for Analytics AWS

Add show-repo-heads script for helping with diagnosis

Enable ecommerce on sandbox configuration conditionally.

Update wiki links in file headers

Add feature flag handle for ENABLE_MOBILE_REST_API

The headers were pointing to the old github wiki. Since we've officially
moved to Confluence, these links should be updated.

pass the read replica hosts list as external variables from secure repo

Adding support for multiple auth credentials for nginx (OPS-952)

mount ebs role

This prevents us from mounting a disk in two places.

This implements a role that consumes a volume list of dicts and ensures
those are all mounted in the expected location on your system as well as
formatting any drives with the wrong fstype.

As a safety feature, it defaults to being unwilling to unmount drives
(since that might result in data loss or mismanagement) and there is a
flag you can -e to enable it.

It is assumed you will run this role passing along your volume list from
your main playbook and secure vars.

OPS-1383: Add role for turning on enhanced networking

Go agent docker Updates

Amazon wants 2.16.4, says elsewhere 2.14.2 is ok and that Ubuntu 14.04's
2.11.3-k is ok but missing some bug fixes.

Updated go-agent dockerfile to override start script so container process captures the correct GO_SERVER_PORT

Set ecommerce JWT_LEEWAY

Makes ecommerce more tolerant of slight clock skew

Added settings for edx-drf-extensions to discovery role

ECOM-3895

Ensure libjpeg-dev is available on Programs hosts

Removing HOSTNAME_MODULESTORE_DEFAULT_MAPPINGS to make preview domain…

TNL-4073

hackathon documentation updates