Update: Add support for su3-signed development builds (ticket #1381)

Full version is used as the su3 version.
Uses same su3 certs as release updates. Users may add additional certs
to ~/.i2p/certificates/router/ as necessary.
Copy echelon's reseed key for use as a router signer.
Unsigned update remains a separate option for now.
Various update subsystem cleanups.

apps/routerconsole/java/src/net/i2p/router/update/PluginUpdateChecker.java

@@ -40,16 +40,6 @@ class PluginUpdateChecker extends UpdateRunner {
     @Override
     public String getID() { return _appName; }
     
-    @Override
-    public void run() {
-        _isRunning = true;
-        try {
-            update();
-        } finally {
-            _isRunning = false;
-        }
-    }
-
         @Override
         protected void update() {
             // must be set for super