Read GPIO key on startup

Create class Presence which will be responsible for
determining and monitoring presence of inventory items
and updating D-Bus accordingly. With this commit
class Presence only reads the GPIO key on startup,
more to come later.

Change-Id: I647ae11d42a813a103e6d9d8922fd0f5b2155132
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
4 files changed