Add lint plugin

[ghoneycutt]

Description

Add a puppet-lint plugin to check for the presence of a newline character at the end of a file.

Motivation and Context

To ensure style compliance and lessen back and forth with pull requests.

[treydock]

That plugin just ensures \n is last character of manifest, it won't catch extra newlines where file ends with \n\n.

[ghoneycutt]

Right, though I saw we were not using it and should.