use diskfile in ssync_sender tests

Change-Id: I7993de98ce3eb4839fa5d72d1b6ce08e4a7c1451
fix expired object deletion

fixes bug #1257330

Change-Id: I49f645abdeba97eafb3ae42ef9e3684c912cfdc6
Merge "use diskfile in ssync_sender tests"
Merge "fix expired object deletion"