util: Add a function for converting MAC addresses

We need to be able to convert a mac addresses from byte form into our
typical human readable string form.

Tested:
    Unit tests pass.

Change-Id: I6e68cfefd4d5962e1125c1b5229e61fce475729a
Signed-off-by: William A. Kennington III <wak@google.com>
3 files changed