Add support for placement API to devstack

Uses lib/placement, but relies on some functionality from
lib/nova. This leads to some weirdness since the nova has
special status in stack.sh. If/when placement is extracted
it may be good to follow the devstack plugin structure
instead.

Because the placement code is currently a part of nova, there
are dependencies in lib/placement on a some $NOVA_* variable
and, if virtenv is being used, the virtualenv used by nova.

Because placement currently runs using nova's configuration
settings, not a lot actually happens in lib/placement: apache
is configured and keystone accounts and endpoints are created.

If PLACEMENT_DB_ENABLED is true then a separate placement db
will be configured.

When complete the initial version of the placement service will
provide support for managing resource providers, inventories and
allocations.

The placement api only runs under mod-wsgi.

Change-Id: I53dd3e6b41de17387a0e179fc9ac64c143b6a9eb
diff --git a/clean.sh b/clean.sh
index 452df02..bace3f5 100755
--- a/clean.sh
+++ b/clean.sh
@@ -46,6 +46,7 @@
 source $TOP_DIR/lib/keystone
 source $TOP_DIR/lib/glance
 source $TOP_DIR/lib/nova
+source $TOP_DIR/lib/placement
 source $TOP_DIR/lib/cinder
 source $TOP_DIR/lib/swift
 source $TOP_DIR/lib/heat