Panic responder (#512)

* feat: add panic responder

* refactor: logOut before removing session

* fix(panic): close app after logOut to avoid crash

* build: reset gradle.properties

mastodon/src/main/java/org/joinmastodon/android/ExitActivity.java

@@ -0,0 +1,24 @@
+package org.joinmastodon.android;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+
+public class ExitActivity extends Activity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        finishAndRemoveTask();
+    }
+
+    public static void exit(Context context) {
+        Intent intent = new Intent(context, ExitActivity.class);
+        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
+        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
+        context.startActivity(intent);
+    }
+
+}