fix stop button; catch and log exceptions better

...ole/java/src/net/i2p/router/web/ConfigClientsHandler.java

...sole/java/src/net/i2p/router/web/ConfigClientsHelper.java

...terconsole/java/src/net/i2p/router/web/PluginStarter.java

...sole/java/src/net/i2p/router/web/PluginUpdateHandler.java

...terconsole/java/src/net/i2p/router/web/WebAppStarter.java