prevent strange appcompat stack overflow

inspiration: http://stackoverflow.com/a/14167949

Fixes #3118
Closes #3119
// FREEBIE

src/org/thoughtcrime/securesms/ReceiveKeyActivity.java

@@ -79,6 +79,7 @@ public class ReceiveKeyActivity extends PassphraseRequiredActionBarActivity {
   protected void onCreate(Bundle state, @NonNull MasterSecret masterSecret) {
     this.masterSecret = masterSecret;
     setContentView(R.layout.receive_key_activity);
+    getSupportActionBar().hide();
 
     initializeResources();