Merge pull request 'Faster shutdown with unwilling thread' (#15) from fasterStop into master

Reviewed-on: SteamWar/PersistentBungeeCore#15
Reviewed-by: YoyoNow <jwsteam@nidido.de>

src/net/md_5/bungee/api/bungeepluginmanager/PluginUtils.java

@@ -74,12 +74,12 @@ public final class PluginUtils {
                 .forEach(thread -> {
                     try {
                         thread.interrupt();
-                        thread.join(2000);
+                        thread.join(100);
                         if (thread.isAlive()) {
-                            throw new IllegalStateException("Thread " + thread.getName() + " still running");
+                            ProxyServer.getInstance().getLogger().log(Level.SEVERE, "Could not stop thread " + thread.getName() + " of plugin " + plugin.getDescription().getName() + ". Still running");
                         }
-                    } catch (Exception t) {
+                    } catch (InterruptedException t) {
-                        severe("Failed to stop thread that belong to plugin", t, plugin.getDescription().getName());
+                        Thread.currentThread().interrupt();
                     }
                 });