Change decorator to webob as doesn't need to be wsgi

This patch changes the decorates in the metadata agents to webob.Request
as they don't need to go through wsgi. Note: wsgi.Request's base class
is webob.Request.

Fixes bug: 1208907

Change-Id: I069635eb67812136d314fc260cebf65886a95597
Merge "Change decorator to webob as doesn't need to be wsgi"