separate partition number from test name

[thousand]

Currently the test name is added into the test's name (https://github.com/trentmwillis/ember-exam/blob/e3579e97a43dfa10f959ddec813544f7983fd085/addon-test-support/-private/patch-testem-output.js#L11). This tightly couples the partition to the test itself, and makes it difficult to have reporting based on individual tests regardless of which partition they're executed in.

Ideally the partition would be included as a separate field somewhere, and then ember-exam would include or patch the reporting side to display that in log output instead. This way other testem reporters used in parallel (like the default xunit reporter from testem) can be guaranteed that the test name will be consistent from run-to-run and include the partition number as metadata if needed.