Poll plugins when connectivity changes. Bug #66.

This should enable us to connect to contacts faster at startup and
whenever a new means of connecting becomes available.

briar-android/src/org/briarproject/plugins/droidtooth/DroidtoothPlugin.java

@@ -172,6 +172,7 @@ class DroidtoothPlugin implements DuplexPlugin {
 				}
 				LOG.info("Socket bound");
 				socket = ss;
+				callback.pollNow();
 				acceptContactConnections();
 			}
 		});