Increase header size accepted as keystone v3 generates large ones.

Encoding of catalog in keystone v3 causes issues for neutron client
to reach to neutron server. Default is of 8K is not enough! At some
point keystone should allow for filtered catalogs but till then...

Change-Id: Ie8c0fa439a24ee266f32aa66985f8ff1eb7619ae
Closes-Bug: #1395125
Merge "Increase header size accepted as keystone v3 generates large ones."