A module for notifications through the Slack.com platform

This module can send messages through Slack.com, and supports all options
available in the "incoming webhook integration".

- text
- channel
- username
- icon_url / icon_emoji
- link_names
- parse
mandatory silly mistake
Don't filter role deps on tags

Also, fixed a bug where the tags were being merged into the wrong
data structure (passed_vars) in _build_role_dependencies()

Fixes #6439
Fixes #5709
docker: add tty and stdin_open options

Useful for development environments.  Setting these options to true
allows you to `docker attach` to a docker container started with
ansible.
Fixes #6542 rewrite test string for osx compatibility
Fixes #6519 Properly handle state=absent in sysctl module
Update credentials.yml documentation and handling

Changes include:

 * Update Makefile to use credentials.yml when it exists
 * Add details on the use of the credentials.yml file to README.md.
 * Update credentials.template comments
Make modules set a valid working directory

Fixes #6546
Merge branch 'issues/6341' of https://github.com/threatgrid/ansible into threatgrid-issues/6341
Fixes #6550 Use shell for pipe lookup subprocess.popen calls
add param to note example for ssh-keyscan

hostnames in the known hosts file are typically stored as Hashed values, calling 'ssh-keyscan' with '-H' changes to output to the Hashed format so that the known_hosts file looks more consistent
Addresses #6550 add integration tests for pipe lookup
Merge pull request #6554 from vyrak/keep-head-state

homebrew: state=head includes --HEAD
Execute commands through accelerate with shell when needed

This fixes an issue related to the new run_command changes, whereby
Popen fails to run a command when an executable is specified + shell=False
and there are multiple positional arguments (see Popen docs for details)
Merge pull request #6556 from andreaskern/patch-1

add param to note example for ssh-keyscan
Change print message to vvv for missing known hosts in ssh.py
Merge pull request #6544 from ramondelafuente/feature/notification-slack

A module for notifications through the Slack.com platform
Update CHANGELOG.md
Make sure all tags are in a list before merging for role deps

Fixes #6557
Merge branch 'threatgrid-issues/6341' into devel