Allow '.' to appear in package release strings.

[bugfood]

Packages for RedHat/CentOS commonly have versions like: 1.2.3-4.el7

Here's an example in the wild: https://cbs.centos.org/koji/buildinfo?buildID=12210 The page contains: "Information for build kibana-4.5.4-2.el7"

...and locally-built packages may follow this pattern, as in the case I encountered.

Without this change, such package versions fail input validation.

Pull request acceptance prerequisites:

• [N/A] Signed the CLA (if not already signed)
• [x] Rebased/up-to-date with base branch
• [N/A] Updated CHANGELOG.md with patch notes (if necessary)
• [N/A] Any relevant docs (README.markdown or inline documentation) updated (if necessary)
• [N/A] Updated CONTRIBUTORS (if you would like attribution)
• [ ] Tests pass CI

[bugfood]

This is a trivial one-character change, plus an 11-character addition to the tests. Do you really need a CLA signature for that?

The tests failed for a reason unrelated to my patch: Debian 7 could not fetch security updates, presumably because it is end-of-life.

[vox-pupuli-tasks[bot]]

Dear @bugfood, thanks for the PR!

This is Vox Pupuli Tasks, your friendly Vox Pupuli Github Bot. I noticed that your pull request has CI failures. Can you please have a look at the failing CI jobs? If you need any help, you can reach out to us on our IRC channel voxpupuli on Freenode or our Slack channel voxpupuli at slack.puppet.com. You can find my sourcecode at voxpupuli/vox-pupuli-tasks

[vox-pupuli-tasks[bot]]

Dear @bugfood, thanks for the PR!

This is Vox Pupuli Tasks, your friendly Vox Pupuli GitHub Bot. I noticed that your pull request contains merge conflict. Can you please rebase?

You can find my sourcecode at voxpupuli/vox-pupuli-tasks

[bugfood]

We are no longer using this patch locally, due to our use of newer packages. If anybody ever needs this, it should be simple to resurrect.

-Corey