MAR-218: Switch to using task imports instead of includes:

- Should result in somewhat faster run, except the includes happen
during planning phase. None of the changed includes will have
problem with this.
- Solves the issue of (included) imported tasks not being tagged
properly, particularly in relation to the mechanism for explicitly
running all handlers.

MAR-218: Switch to using fully-qualified collection names for all tasks:

- Ensures there is no ambiguity when invoking a module.

MAR-218: Quote all octal values in YAML files:

- Fixes linting errors, and ensures there is no ambiguity in case of
YAML specification changes.

MAR-218: Fix include invocations:

- The old include keyword/task has been deprecated in favour of more
explicit include_tasks one.

MAR-192: Drop the Python 2.7-specific packages from installation:

- These are leftovers from previous work for dropping the Python 2.7
support.

MAR-152: Fix idempotence issues with web_server role:

- Reload configuration of PHP-FPM to ensure changes are picked-up.
- Install base packages for PHP applications prior to creating the
directory containing unix socket files (so the package installation
would not change them back).

MAR-148: Fixing linting errors:

- Do not compare against booleans when value is already boolean in
"when" conditions.
- Use pipefail in conjunction with setting the shell to Bash when
extracting the backup encryption key IDs.
- Do not compare variables to empty strings in "when" conditions. This
change currently works only for complex variables (stuff can break
badly in case of simple variables in current default Ansible
configuration).
- Fix missing space in one of Jinja2 templates.

MAR-134: Fix Ansible warning about use of apt and with_items:

- The apt module can accept list of names already, and with_items is
considered to be deprecated in this regard (otherwise it would
end-up running one apt command per item).
- Changed multiple roles where apt was used together along with_items.

MAR-134: Make sure the Python setuptools are available for virtualenv use:

- Must be present for pipreqcheck virtual environments to get setup
correctly.
- Should be a good idea to include it in the default web server config
too.

MAR-135: Switch to using run_handlers instead of handlers as variable:

- Updated all roles to now depend on run_handlers being set to True in
order to force execution of handlers.

MAR-132: Added support for Debian 9 (Stretch) to web_server role:

- Introduced internal parameters for controlling differing package
names, service names, and paths for PHP FPM package.
- Added Debian 9 machines to Molecule configuration, including the
client machine.
- Restructured slightly preparaiton playbook to support both Jessie
and Stretch.
- Added custom pytest fixture for having a better way to determine
expected package names etc related to PHP.
- Created copy of private key/certificate pair used for testing of
mandatory parameters (to be used with Stretch machine).
- Fixed invalid specification for hosts on top of which the
connectivity test should be run.
- Updated a couple of task names (avoiding to reference PHP 5).
- Updated documentation.

MAR-129: Updated web_server role for Ansible 2.5.x and new Molecule:

- Fixed linting errors.
- Include global linting configuration file in the test configuration.
- Moved variables from the test playbook into group variables.
- Updated how hosts are referenced in tests.
- Fixed deprecation warnings.

MAR-114: Updated task syntax for web server/application roles:

- Updated web_server, php_website, and wsgi_website roles.
- Added and removed quoting where it makes sense.
- Switched to using expanded syntax (instead of one-liners).
- Updated ordering of arguments in task definitions.

MAR-32: Implemented tests for web_server role:

- Updated test playbook to deploy some additional test tools.
- Use expanded syntax for deploying TLS keys and certificates in order to
preserve tabs.
- Added a number of tests that should cover full functionality of the server.

MAR-32: Added initial scaffolding for testing web_server role:

- Added Molecule configuration for for bringing up a couple of instances.
- Added test playbook that sets-up test instances.
- Fixed issues with file mode in tasks (added leading 0).
- Added test data (TLS private keys and certificates).
- Added dummy test file.