allow middleware configuration from app config
allow middleware configuration from app config

From markmc's proposal:
http://lists.openstack.org/pipermail/openstack-dev/2012-July/000277.html

For backward compatiblity, configuration from paste-deploy INI is used
if it exists. If not, section [keystone_authtoken] in  global
configuration is expected, with the same parameter names.

Requires application using global cfg.CONF object (nova and glance since
folsom-2) and before there's openstack.common library, attempts to use
copy/pasted <application>.openstack.common.cfg

DocImpact

Change-Id: If6aa22280f4ce2cc698d99a130b5792dab808363

varunarya10/keystonemiddleware