Updated sshd defaults for Ubuntu 18

Merged #103, which gives current sshd defaults for Ubuntu 18. Thanks @mfredholm.

Fix for minor bug in systemd unit file configuration

#93 Fixes incorrect argument parsing in the new systemd code. Thanks to @tterranigma

Adds sshd_enable to disable role entirely during a run

#91 Add a big toggle to stop the role running, sshd_enable. Thanks @tterranigma

Multi daemon support, backup sshd config, updated sshd config items, Ubuntu 18 support

Quite a large change in the internals, so bumping to the minor rev.

#89 Adds the ability to install multiple systemd unit files and so manage multiple sshd daemons. It also exposes a number of previously internal variables so the location of the sshd binary, config file and so on can be controlled from the calling play. See sshd_install_service and Secondary role variables in the README.md for more information. Stirling work by @tterranigma.

#84 adds sshd_backup, which when set to true will backup the sshd config. Thanks to @easonand

#87 Fixes a long standing bug with sshd_match variable being reused and adds new sshd options as well as improvement to the CI tests. Thanks to @pillarsdotnet

#88 Addes Ubuntu 18 defaults, copied from the defaults for 16. Thanks to @dduong42

Container Linux by CoreOS support

Only one change - #82 add Container Linux by CoreOS support. Thanks @beyondbill!

AMZN Linux fix

Merges #79 to fix a typo in the AMZN Linux vars file. Thanks @beyondbill

Arch Linux, Ansible 2.5, Debian 9, coding standards

Many thanks to D4N, TimJDFletcher, pieterlexis, tterranigma, jamatute

Change ansible_pkg_mgr to package #61
Fix type in daemon spelling #62
Use listen: in handler #64
Remove tags from role #63
Add Arch Linux defaults #67
Add StreamLocalBindUnlink option #74
Remove obsolete options from Debian 9 defaults #76
Fix for ansible_virtualization_type not defined in Ansible > 2.5 #78

Bug fix binge

Bunch of minor bugs that have been kicking around for a while have been fixed.

• Role no longer manages /var/run directory.
• Warnings under Ansible 2.3 resolved.
• Added a note about RHEL 7 and UsePAM to the variables file.
• Removed a cyclical symlink in the tests/roles directory and reworked the dev Vagrantfile accordingly.

This does change functionality, hence the bump to 0.5

Fix sshd_match blocks

Fixes bug where sshd_match blocks were duplicates. Thanks to @troyfontaine

Fix to server state. Update to galaxy name.

• Updated the service state in the task set state to 'started' rather than the obsolete 'running'. Thanks to @Fuegoel

• A long standing issue I was having with galaxy has been resolved, making the canonical name of this role willshersystems.sshd. Thanks to @mschneiderwind for pointing out the change hadn't been made in the readme.