esp8266-sensor-node v1.0.4

The esp8266-sensor-node release v1.0.4 adds support for a new /health API endpoint. Among the details included in the response to requests to this endpoint are the following:

• system uptime (milliseconds since start)
• memory utilization - free heap memory (bytes)
• module supply voltage - Vcc (Volts)

These values each include a ISO 8601 formatted timestamp. The timestamp is populated from the internal clock, which in turn is set from, and synchronized periodically with an NTP server.