- fix api gradle deprecation, add warn comment in gradle wrapper
- buildtools 27.0.3 needs to be added w/license accepted
- install SDK API 16 to match emulator API 16, remove extra tools
- tools components entry twice per Travis docs
- only including build-tools 26.0.2 as it is default per my read
- only including one android API for the build
- removing non-existent extra-android-support
- changing from API-22 emulator to API-16 per performance documentation on web
- removing "no-skin" emulator argument as it is not supported
- upgrade to gradle 4.5.1 / gradle plugin 3.1.2
- alter gradle dependencies to modern fine-grained declarations
- move api build targetSdk to match main build targetSdk
