Add dependency-scope-maven-plugin

[jhaber]

Readme for the plugin is here, background for the PR is in #30

[stevenschlansker]

Tested on a couple of moderately complex projects - the only error reported was totally legit; we had junit sneaking into our build in a couple places. Initial impression is very positive!

[jhaber]

Great! Our most common failures are related to junit/mockito/assertj sneaking in. I'm wondering if it's worth adding an exclusions parameter to the plugin so we can just ignore these libraries for convenience. In any case, those exclusions wouldn't belong in basepom so it probably doesn't affect this PR

[stevenschlansker]

I found a couple more flags like you describe of junit. A couple of them were in integration tests that had unusual project layouts, I just disabled the plugin for that part of the tree. Still nothing particularly onerous.

[jhaber]

Thanks! Let me know if you find any issues with the plugin or want any features added