shared: Add opaque BuxtonResponse

Use BuxtonResponse to wrap data returned from the daemon.
real API

Signed-off-by: William Douglas <william.douglas@intel.com>
use buxtonstrings for things

Signed-off-by: William Douglas <william.douglas@intel.com>
More API rework

bt-daemon and libbuxton almost compile now. Need to figure out transition for
label being removed from BuxtonData will look like.

The daemon should be fixed for reading client messages with two part keys but
client (mostly test) will also need to be updated to reflect the client gets
two part keys back from the daemon.