Release LocationLayerPlugin 0.8.1

[Guardiola31337]

Changelog

• Prevent from showing the location layer on every location update #641

Release checklist

• Cut the release branch
• Run through testapp/demo app and test all activities
• Update README.md
• Update CHANGELOG.md
• Change version name to 0.8.1 in gradle.properties
• Publish 0.8.1 artifact to Maven Central
• Change version name back to 0.9.0-SNAPSHOT
• Merge the release branch back to master
• Tag v0.8.1 in GitHub

Post-release @langsmith

• Update plugin's version #s in https://github.com/mapbox/mapbox-plugins-android/tree/master/plugin-locationlayer
• Update constants.js file in android-docs repo
• Generate updated javadocs and add to android-docs repo
• Update the version # in the Mapbox demo app
• Update the version # in the Studio Preview app
• Update the version # in voyage
• Update the version # in china plugin demo

/cc: @mapbox/android

[langsmith]

👏 🥇