Add vagrantfile/environment for a working multinode vagrant with neutron

Change-Id: If567c11eea2ee1398efda4d3740899df449e28ad
Implements: blueprint reference-havana-vagrant
Added documentation about databags

When you don't use the developer_mode you need to have crypted databag to store the openstack password.
This patch explain all the items you need and add some example of the items schema.

Change-Id: I67d6bfecb9df2da92af064793ad6d3676f93bbc8
Closes-Bug: #1282457
Merge "Added documentation about databags"
Merge "Add vagrantfile/environment for a working multinode vagrant with neutron"