First pass at a reasonably high level test.

This test requires a lot of dependencies, but does a reasonable test and
covers all the basics I'd expect for a "dist" share dir.

Creates both mock source and install trees, and builds one and installs
to the other.

Though I'd strongly recommend a global 
```diff
-File::Sharedir
+File::ShareDir
```

First and will rebase on request if that is done.