Add comment line for example groups

[gburgett]

Some Tap formatters, like tap-xunit, use comments in order to delineate groups of assertions. I felt this was a good spot to add info about the example groups.

This produces TAP output like the following:

Randomized with seed 55555
1..999
# API
# API.FooController
ok 1 - API FooController get root is successful
ok 2 - API FooController put root does something
# API.BarController
ok 3 - API BarController get with ID is successful