3.2.8 Release

Release Notes

• Remove dependency on jcenter by @jkasten2 in #518
  • Resolves #528, #516, & #248
• Fix CI issue by @iAmWillShepherd in #524
• Make license file compatible with tools like LicenseBat by @iAmWillShepherd in #527
• Updated to OneSignal-iOS-SDK 3.10.0
• Updated to OneSignal-Android-SDK 4.6.6
  • Resolves #494

Full Changelog: 3.2.7...3.2.8