Background services changes in Android 8

Some material to study in order to upgrade some old code:

• https://android.jlelse.eu/keep-those-background-services-working-when-targeting-android-oreo-sdk-26-cbf6cc2bdb7f
• http://www.techeos.com/posts/android-jobintentservice-oreo.html
• https://medium.com/til-kotlin/jobintentservice-for-background-processing-on-android-o-39535460e060
• https://medium.com/google-developers/scheduling-jobs-like-a-pro-with-jobscheduler-286ef8510129

In addition, notification channels need to be created for any notifications on API >= 26. Notification channels are useful. They allow grouping of notifications so that end users can disable or enable them as they see fit.

• https://code.tutsplus.com/tutorials/android-o-how-to-use-notification-channels--cms-28616