Add example variable api_branch_or_tag to file

Add to roles/api/vars/development.yml.dist
Update required Ansible version in README
Add missing parameter to ansible-playbook invocation

Add the necessary --extra-vars parameter to the instructions for
performing an installation.  The initial_run=true setting is
necessary to avoid a failure in the ElasticSearch setup.
Remove outdated comment from Vagrantfile.dist
Add usage comment to dev_all.yml playbook

This is related to commit d04827eeb64
Add munin monitoring

Also remove nginx_status handlers from existing Nginx configurations.
Add munin stats plugins for munin_master
Add missing restart for munin plugin activation

In the monitoring_web role.