Ensure that CMakeInfo provides a uniform API for Nodes and Nodelets

[ChrisTimperley]

It might be worth adding this as a comment (or issue) since this breaks interface expectations so that we can come back to it later. In the longer term, it probably makes sense to strip out the package name from the class_name tag when building the CMakeInfo in ROSWire for consistency.

Originally posted by @ChrisTimperley in cmu-rss-lab/rosdiscover#207 (comment)