3.8.0 Release

OneSignal Email support

• See the OneSignal Email Quick Start Guide for more details.

Other mis fixes

• Fixed rare java.lang.SecurityException exception. Issue #427
• Work around for Android Marshmallow 6.0 getActiveNotifications bug. Issue #422
• Rare proguard issue with JobIntentService on Android Oreo 8.0 builds. Issue #424