Linter will check packages submitted for CI build. If error was found,
build will not be allowed.
To ensure that all build.sh scripts are consistent and have at least
minimal allowed quality, linter is permanently enabled for all branches
and pull requests.
Update the android sdk build tools from 27.0.3 to 28.0.1, bringing
in d8 which is replacing dx.
This needs an update of the Docker image, so run scripts/update-docker.sh
to update it.
Fredrik Fornwall
Leonid Plyushch
Wetitpig