Includes code from https://github.com/consp1racy/android-support-preference
License: Apache License v2.0

This commit renames identicons to avatars in field names, and uses an ImageView
derivative to show the identicons, which should make implementing #214 easier.

Also removed unnecessary adapter notifications in various places.

Whether or not a class needs to run as a service is an implementation decision.

also run setting the default preferences in a background thread

Closes #184

Due to the nature of how Android app install/uninstall works without
root, this requires manual confirmation after a panic was triggered.

Closes #211