See merge request !24

usually pointing to proper compilator for respective platform.

coupler1 and coupler2 are subscribed over keep-alive network implementation
over Pub/Sub to coupler3.
Coupler3 is sending heart_beats every 10ms and if not heart_beat is received
by coupler1,2 within 50ms they both go to "safe" mode.

Do not subscribe to Pub/Sub in case we actually do not explicitly have configured so. Printouts for better traceability.

See merge request nexedi/osie!22