Adds a unit test to verify the change made in [1], i.e. that
swift-object-info will read from .meta and .ts files as well
as .data files.
[1] change I43966d371218ad39414e9282cde579e48370a2a7
Change-Id: I82dde36e3a96db1a21cfe9a4cca0d941e543dfd0
Related-Bug: 1425679