Infer rootwrap arguments from project

We can infer the binary and configuration paths just from the project
name and expanding this to the known *_DIR & *_BIN_DIR variables.  A
similar thing is done for policyd settings

Change-Id: I7c6a9fa106948ae5cbcf52555ade6154623798f1
diff --git a/lib/nova b/lib/nova
index 7d2145b..da288d3 100644
--- a/lib/nova
+++ b/lib/nova
@@ -298,7 +298,7 @@
 
     install_default_policy nova
 
-    configure_rootwrap nova $NOVA_BIN_DIR/nova-rootwrap $NOVA_DIR/etc/nova
+    configure_rootwrap nova
 
     if [[ "$ENABLED_SERVICES" =~ "n-api" ]]; then
         # Get the sample configuration file in place