Fix a name clash

Rename class attribute `Media.path` to `Media.path_`. This prevents the
attribute from conflicting with the method of the same name.

Fix #1429.
Merge pull request #1432 from Ichimonji10/name-conflict

Fix a name clash
Port old API tests for repositories

Completely rewrite existing tests in module `test_repository_v2`. Make them more
terse, efficent and thorough. Drop module `test_repository`, as the "v2" module
now performs its responsibilities.