specs: Add sample template for spec definitions

specs: Add sample template for spec definitions

In order to elaborate the design of more complex requirements
in an open source manner, create a specs folder to contain
detailed specifications for each requirement.

This sample template is taken directly from
https://github.com/openstack/nova-specs/blob/master/specs/mitaka-template.rst

This sample will be modified in other patches.

Change-Id: I945271c1ca7299e03f33b24f5829135bfb4761ea
Signed-off-by: Mark D. Gray <mark.d.gray@intel.com>
Reviewed-by: Billy O'Mahony <billy.o.mahony@intel.com>
Reviewed-by: Tom Herbert <therbert@redhat.com>