Update documentation to use keystoneauth name

Update documentation to use keystoneauth in the proxy server pipeline.  Change 5e372016 added
pipeline checking and explicitly looks for keystoneauth name, so README should match.

Also update package name for s3_token middleware to be keystoneclient, not keystone.

Closes-Bug: #1381758
Change-Id: I0d769e47ffc32725c1df2def4d9d46c25474132e
Merge "Update documentation to use keystoneauth name"