Rename `traverse` sub-routine to `traverse_cookbooks`.

Change naming of `traverse` sub-routine,
because the `traverse_cookbooks` is more intuitive.

This commit refs #262.
Add sub-routine, named `traverse_tests`.

Add `traverse_tests` to list the changed tests.

This commit refs #262.
Refactor the generation of node json file.

Refactor the generation of node json file,
in order for it to be more intent-revealing.

This commit refs #262.
Generate Rakefile for serverspec tests

This commit refs #262.
Merge branch 'id/262' into dev