Add instructions on setting a volume to read-only

This patch adds a short section on how to set a volume to read-only.

Change-Id: If3658151b84472c552299bd657e946a3b71a2871
Closes-Bug: #1298140
Merge "Add instructions on setting a volume to read-only"
Removed keystone_ec2_uri from heat.conf

keystone_ec2_uri doesn't exist anymore, setting auth_uri is now sufficient.

Change-Id: I861641190b72b9b7cc6ab2a77e3767bd581b6517
Fixed mongodb package name for Debian

Use mongodb-server instead of mongodb which is a meta-package that will
install the unneeded mongodb-dev package.

Change-Id: I36bdf734a07c57b637860ec6002ea2c284e415a5
Merge "Fixed mongodb package name for Debian"
Merge "Removed keystone_ec2_uri from heat.conf"