Assert X-Newest and X-Backend headers are propagated to symlink target
Assert X-Newest and X-Backend headers are propagated to symlink target

Adds some assertions to verify that X-Newest and X-Backend-* headers are
copied from an original object GET requets to the symlink target
request.

Change-Id: Idce92edd002dec34f5dbc5d3c28a4cbbd2fbdc60
Related-Change: I838ed71bacb3e33916db8dd42c7880d5bb9f8e18

smerritt/swift,swiftstack/swift,nadeemsyed/swift,matthewoliver/swift,matthewoliver/swift,tipabu/swift,nadeemsyed/swift,tipabu/swift,nadeemsyed/swift,smerritt/swift,swiftstack/swift,openstack/swift,nadeemsyed/swift,openstack/swift,openstack/swift,tipabu/swift,swiftstack/swift,openstack/swift,tipabu/swift,smerritt/swift,matthewoliver/swift,matthewoliver/swift,smerritt/swift