dont fail UUID generation if we cannot get hwaddr
dont fail UUID generation if we cannot get hwaddr

Bin's machine cannot. Maybe it's expected on windows. Anyway I'm made
code way more robust. Now we sort all known interfaces and try to pick
least bad.

Change-Id: I1d2c6de664992551249269f4af879df04a8ed99b
Reviewed-on: http://review.membase.org/5576
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

pavel-blagodov/ns_server,ceejatec/ns_server,vzasade/ns_server,membase/ns_server,nimishzynga/ns_server,mschoch/ns_server,nimishzynga/ns_server,membase/ns_server,daverigby/ns_server,ceejatec/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,vzasade/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,nimishzynga/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,vzasade/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,daverigby/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,mschoch/ns_server