Added a device attribute to capabilities - In progress

Followed the kernel physical memory reservation convention
with devices. Devices that are possessable by userspace
are created as boot-time capabilities and placed under the kernel
resources devmem_free capability list. Any userspace container
that is defined with the possession of the device would delete the
device capability making it unavailable to further requests.

include/l4/generic/container.h

@@ -60,6 +60,7 @@ struct cap_info {
 	unsigned long start;
 	unsigned long end;
 	unsigned long size;
+	unsigned int uattr;	/* User-level attributes (like device types) */
 };