WeatherPush: Push station config changes

[davidrg]

Would be nice if WeatherPush could transmit station config changes. This would include:

• Anything data in the station table (except for addition of new stations)
• New image sources for a station

This would require:

• Database broadcast notifications on station or image source changes
• WeatherPush queries out the changes and transmits them (as JSON probably) in a special StationConfigUpdate message
• Remote WeatherPush server receives the data, updates its database, then transmits a message back confirming what its done. This will allow the WeatherPush client to update its running config if new image sources, etc, have been added.
• Pushing of station-config should be opt-in via config on both client and server
• Bonus points: support pushing new stations. This again would be opt-in on both client and server.

Ideally this would come after #125 and we'd require doing this over a TCP+SSL connection.