Currently a HTTP_REFERER (Referer) header isn't passed down to
subrequests. This means *LO subrequests to segment containers
return a 403 on a *LO GET when accessed by requests using referer
ACLs.
Currently the only way around referer access to *LO's is to make the
segments container world readable.
This change makes sure the referer header is passed into subrequests
allowing a segments container to only need to be locked down with
the same referer as the *LO container.
This is a 1 line change to code, but also adds a unit and 2 functional
functional tests (one for DLO and one for SLO).
Change-Id: I1fa5328979302d9c8133aa739787c8dae6084f54
Closes-Bug: #1526575