Put staticweb middleware after keystoneauth in proxy pipeline

Put staticweb middleware after keystoneauth in proxy pipeline

The staticweb middleware needs to be put after authentication
middlewares to ensure correct functionality as documented in
http://docs.openstack.org/developer/swift/middleware.html#staticweb

Without this Swift sends a HTML response even if the request was done
using a X-Auth-Token. This might result in a faulty handling of the response on
the client side; for example, "swift stat containername" would report an empty,
private container, while the container might actually be public readable with
data stored in it.

Closes-bug: 1494896
Change-Id: Id48840e0041f8d272e08def292fbedfaf76bbfbb
Co-Authored-By: Christian Schwede <cschwede@redhat.com>