Parameterize the endpoint prefix

The endpoint prefix for keystone endpoints is now configurable (defaults
to AUTH). This will allow for easier integration with SwiftStack
which requires that the endpoint prefix not be AUTH.

Change-Id: I102008aad86c0e35e3020961119a56c81da973f3
Add read_affinity, write_affinity support to proxy

This optionally provides the ability to configure read and write affinity
in proxy-server.conf.
Documentation: http://docs.openstack.org/developer/swift/admin_guide.html

Change-Id: Iea5aa6f73ddbdef119c5e70b29820c43640f0dac
Merge "Parameterize the endpoint prefix"