Make beacon-server start from blcontrol framework (instead of dserver)
In general, in order to start (some of) the device servers, the beacon-server should be running.
The proposal is to start it automatically as a special daemon at the beginning of the blcontrol sequence.
The start-up configuration would be stored in local/BLISS_ENV_VAR:
BEACON_DB_PATH, BEACON_PORT, BEACON_WEB_PORT, BEACON_START
The 'make install' target adds those variables at the end of BLISS_ENV_VAR, if not present. If BEACON_START is not given (the default), beacon-server is started only if running in the TANGO_HOST.