Remove WritableLogger from wsgi
Remove WritableLogger from wsgi

Eventlet 0.17.2 allows the passing of logger instance directly now. This
patch removes the WritableLogger code.

Change-Id: I46049c9bb6b2388d83ae264696499a6987087c51

stackforge/senlin,tengqm/senlin-container,stackforge/senlin,tengqm/senlin-container,openstack/senlin,openstack/senlin,openstack/senlin