0.12.4rc1

0.12.4 is primarily a maintenance/bugfix release.

Callback changes:
- Task results as recorded by ARA are now "filtered" by Ansible's
  _dump_results method [1]. This will only be effective on task recording
  moving forward, it will not edit previously recorded playbooks.
  The _dump_results method strips Ansible 'internal' keys (_ansible_*)
  from the task results and also respects the 'no_log: yes' task directive.
  Prior to this change, ARA did not respect the no_log directive and
  recorded the raw task results as well as all the Ansible internal keys.
  Task results should be cleaner now and be properly censored when using
  'no_log'.

Internal changes:
- Refactor of ARA's configuration module to fix issues in order to properly
  detect configuration parameters like booleans or lists. This refactor
  also brings cleaner backwards and forwards compatibility from Ansible 2.1
  through 2.3.
- Fixed issue to prevent PBR from throwing exceptions when overriding the
  version
- Different changes in both the CLI and the testing framework in order to
  bootstrap and teardown the application properly to prevent context from
  leaking where it shouldn't be

UI changes:
- Javascript datatables in the UI where most of the content is displayed
  will now throw warnings in the background (javascript console) rather
  than in the foreground (javascript alert). These warnings are fairly
  expected, especially in the case of incomplete or interrupted playbooks.
- Adjust wording when notifying users about a playbook that is incomplete
  or was interrupted to make it more straightforward
- Performance improvements on the home and reports page, more optimization
  will follow in the future.
- Fixed an odd problem where certain webservers (ex: nginx) would not behave
  well for the statically generated version of the reports.

CLI changes:
- The "ara generate html" command will now suppress
  "MissingURLGeneratorWarning" warnings by default. A new configuration
  parameter 'ignore_empty_generation' was introduced to revert back to
  the previous behavior. For context on this change, see the commit [2].
- Alembic messages that are not related to migrations are now sent to the
  background.

Database:
- Fix PosgreSQL support, add documentation for using it it and provide
  instructions for integration testing it

Documentation:
- The project now has a manifesto [3] to express in writing the project's core
  values and philosophy
- Improved contributor documentation
- Added a FAQ on running the ARA callback and the web application on
  different machines

[1]: https://github.com/ansible/ansible/blob/b3251c9585b0b0180fcdf09748e9a0dc439bc1aa/lib/ansible/plugins/callback/__init__.py
[2]: http://git.openstack.org/cgit/openstack/ara/commit/?id=440dac3789ca12c50f63a89850a7e65c1ac93789
[3]: http://ara.readthedocs.io/en/latest/manifesto.html