Modifying self.json on configuration change

[RBerliner]

self.json is not rewritten on server restart (or on the restart of signalk-java via mvn exec:java). Instead, the old self.json is reloaded.

To in corporate changes to self.json following changes to signalk-config.json using the config panel, you must halt the system, delete self.json and restart. This has the consequence that the new resources key does not contain the charts so you must reload the charts.

[rob42]

The self.json contains the vessels tree, and charts are in resources in vessels.resources, so they go away too.
Need to save resources separately, like config, so we can keep them. There are other items in vessels that should be kept too, vessel name, communication, design etc...

Also AIS vessels clutter the display after a restart (until they expire in 10 min). They can probably be removed before saving self.json. Or at least dropped on reload.

[rob42]

Added removel of ais targets on restart to master, but only in dev builds for now