Revert "http-service: Allow Cross-Domain requests from localhost, for testing"

crossdomain.py wasn't installed as a part of `make install` so wouldn't
appear in production in the docker container.  Instead of fixing that
this commit removes crossdomain.py entirely as it was only useful for
development when not using a reverse-proxy, and ultimately a reverse-proxy
is required anyway.

This reverts commit 184f337c4019a9686a6c4644a74059a18ef3543d.