Add resource CRUD to connection class

Once a user has a resource, there is no need to use the proxy
to perform operations on it.  These CRUD methods allow the user
to perform them direction on the object.  For instance:

    project = conn.identity.find_project('foo')
    project['enabled'] = False
    conn.update(project)

Change-Id: I801de6b56f2f44c568b6edcf9c1429014f42a65f
Merge "Add resource CRUD to connection class"