Add web server for clock configuration and monitoring

[Phil Hord]

Web pages could allow configuration of device:
1. MAC address
2. Static/Dynamic IP address
3. Password
4. Time zone
5. DST enable
6. NTP server(s)
7. NTP poll time (daily, hourly, etc.)
8. Clock skew correction

Control and monitoring of device:
1. Manual correction controls (RUN, Advance 'n' hours, Advance 'n' minutes)
2. Debug log / activity monitor
3. Detected clock skew