tests: Rename 'test_person'

Reflect the purpose of these tests - validation of the autocomplete
feature - in the filename.

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Reviewed-by: Andy Doan <andy.doan@linaro.org>

diff --git a/patchwork/tests/test_person.py b/patchwork/tests/test_completion.py
similarity index 100%
rename from patchwork/tests/test_person.py
rename to patchwork/tests/test_completion.py