Includes:

• Adding Shifter implementation Adding Shifter implementation #922
• Fix v4.1.1 release

Release checklist @Guardiola31337

• update this repo's README.md file with new SNAPSHOT version
• Change version name to 4.2.0 in gradle.properties
• Publish 4.2.0 artifact to Maven Central
• Change version name to 4.3.0-SNAPSHOT
• Update CHANGELOG.md
• Tag v4.2.0 in GitHub
• Update Maps SDK dependency

Post-release @langsmith

• Add the Mapbox Java packages' API reference docs to the their respective folders in /android-docs/api/mapbox-java
• Update the constants.js file in android-docs repo so that compile 'com.mapbox.mapboxsdk:mapbox-sdk-services:x.x.x' line is updated in the Gradle section of the MAS overview page
• Update the Android demo app
• Update version # in config files in /help @langsmith
• Update version # in Studio Preview

/cc: @mapbox/android