Core: Apply a trivial versioning scheme

This patch introduces a trivial versioning scheme in place for the
upcoming v1.0 release. A more grand scheme encoding the git information,
toolchain information, and other environment parameters will be discussed
and rolled out in future.

Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I4fea7df4f008ea3709071e5c414200ae17ac9687