the default components will be controlled and already pre-installed by the chef cookbook: https://github.com/travis-ci/travis-cookbooks/blob/master/ci_environment/android-sdk/attributes/default.rb#L21-L36

the default license to accept (`android-sdk-license-bcbbd656`) is directly handled by `android-update-sdk` extra script.

Since `android update sdk` always re-install every requested package (not a *clever update*), I think it is optimal to let the user decide whether or not to do something at the beginning of the build.