Docker image for building Android projects

This is a base image for building and testing Android images. It contains the latest Android SDK and a non-root user named android with a password of android

The emulator must be called with $ANDROID_HOME/tools/emulator due to strange path issues that will throw errors, or use older option sets.

• Using Ubuntu 16.04 for base

• $ANDROID_SDK_ROOT => $ANDROID_HOME
• User android now has a password of android and can use sudo