Listen, when used on JRuby, does have have access to synchronous
filesystem events. Instead, it uses a listen loop which has some
delay in registering filesystem changes. These tests checked for
events to have fired immediately after making filesystem changes,
which did not allow time for that listen loop to trigger. I added
`wait` to each test, as a few already did, to ensure the events
fire. With these changes, the tests are all green on JRuby.