Fix the NPE within OneSignalCacheCleaner.java (#1047)

* Boolean expression for closing of the cursor has a `NPE` because of the usage of `&` instead of `&&`

Author: mikechoch

OneSignalSDK/onesignal/src/main/java/com/onesignal/OneSignalCacheCleaner.java

@@ -113,7 +113,7 @@ public void run() {
                 } catch (JSONException e) {
                     e.printStackTrace();
                 } finally {
-                    if (cursor != null & !cursor.isClosed())
+                    if (cursor != null && !cursor.isClosed())
                         cursor.close();
                 }