The file name in META-INF/services must be the fully qualified
interface name; the content the fully qualified implementation class
name.
This was broken in commit 9683bc71.
Add a test for the default factory being found by the ServiceLoader.
Change-Id: I1f180d7f60e5c1e74a39bbd9a5f0099bd8343e21
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>