Preparation for Ficus devstack release

* No need to download our specific version
* Use officially supplied FF 45

boxcutter/ubuntu1604 needs recent Vagrant, so pin at least 1.8.7

Xenial doesn't have Python 2 that ansible needs, so use ansible-bootstrap.sh to get it, though that might be way more than we need.

Use a .bashrc.d directory for more flexible configuration

We don't need git_2_0_1 any more, since we are on Ansible 2 now

set insights db host back to localhost

Can't be certs_user to set these permissions correctly.

Explicitly set permissions for certs config.

Over tagged task and overrides.

Update bootstrap to be able to run a subset and run a subset when launching an instance.

XQWatcher user doesn't have permissions to update supervisor or restart it.

Supervisor needs permissions for two different users.

To check for migrations it needs to be able to read the lms.env.json and
lms.auth.json files for edxapp, and to be able to link services it needs
to be supervisor.

Set virtualbox network to virtio for speed

Revert "remove ec2_ami_2_0_0_1 module so we begin using the one built in"

Jibsheet/xenial ansible2 mongod fixes