Add a class to detect the ProjectType of a gradle project.

This may be used when applying a plugin if it needs to behave differently on a top level organizational project or a leaf project which produces artifacts.
Merge pull request #2 from rspieldenner/project_type

Add a class to detect the ProjectType of a gradle project.
Improve ProjectType tests to also test a deeper nesting structure
Merge pull request #3 from rspieldenner/projecttypetests

Improve ProjectType tests to also test a deeper nesting structure