prevent strange appcompat stack overflow

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

Fixes #3118
Closes #3119
// FREEBIE

res/values/themes.xml

@@ -238,6 +238,7 @@
         <item name="android:windowContentOverlay">@null</item>
         <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
         <item name="android:windowActionBar">false</item>
+        <item name="android:windowTitleSize">0dp</item>
         <item name="android:windowActionModeOverlay">true</item>
 
         <item name="android:colorBackgroundCacheHint">@null</item>

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();