Fix custom recurrence dialog issues

* Wrong text color
* Dialog was duplicated on rotate

app/src/main/java/org/tasks/repeats/CustomRecurrenceDialog.java

@@ -519,10 +519,12 @@ public class CustomRecurrenceDialog extends InjectingDialogFragment {
   }
 
   private void repeatUntilClick() {
+    if (getParentFragmentManager().findFragmentByTag(FRAG_TAG_DATE_PICKER) == null) {
       long repeatUntil = DateTime.from(rrule.getUntil()).getMillis();
       newDatePicker(this, REQUEST_PICK_DATE, repeatUntil > 0 ? repeatUntil : 0L)
           .show(getParentFragmentManager(), FRAG_TAG_DATE_PICKER);
     }
+  }
 
   private void updateRepeatUntilOptions() {
     repeatUntilOptions.clear();

app/src/main/res/layout/frequency_item.xml

@@ -13,4 +13,4 @@
   android:ellipsize="end"
   android:singleLine="true"
   android:textAlignment="viewStart"
-  android:textColor="?attr/colorOnPrimary"/>
+  android:textColor="?attr/colorOnSecondary"/>