(PDK-1175) pdk new unit_test

[rodjek]

Introduces a new pdk command pdk new unit_test which can be used to generate a skeleton unit test for objects like existing classes and defined types. This is not intended to provide retrospec like functionality, but simply provide people with the same "it compiles" skeleton test that the existing generators do automatically.

[coveralls]

Coverage increased (+0.2%) to 91.961% when pulling cf5b986 on rodjek:test_gen into b00c515 on puppetlabs:master.

[scotje]

Overall this is looking good, I will go over in more detail on Monday.

I'm with @glennsarti though, I think we need to workshop the subcommand/action UX a bit.

Perhaps we can dark-ship this in the August release and get the functionality tested while we finalize the UX?

[glennsarti]

@rodjek and I had a chat via Slack, and general consensus is pretty much what @scotje said:

1. Yes the name probably needs to change

2. We lack shared context around what each Verb actually means so right now it's too easy to bikeshed

3. It's safe to ship this as "experimental"/"dark ship", and once we get a better naming standard we can move the functionality there.

[glennsarti]

All ready for merge except to mark this as "experimental" in the summary/comments of the CLI

[glennsarti]