Rearrange directory structure:

Motivation - make it easier to properly order software
installation, config installation, db schema updates, etc,
and fit a more idomatic ansible directory structure by:

  - move most services out of playbooks into roles
  - move site.yml to root of repo
  - move custom modules to /library


Nice side effects:
  - integration test passes on first run
  - start things in dependency order, so that no errors
    appear at the beginning of logs
  - don't start monitoring until everything is up.
  - fewer things inaccurately show as duplicated on
    subsequent runs
  - remove some redundant tasks