move docker run logic into Docker utility class
set working directory to $WORKSPACE
remove detailed docker execution from build log
debug option
make message more explicit
note on issues #8703
not final, so it can be enabled from groovy console
run as user:group, not just user
instead of using a long 'sleep' command, allocate a tty to block 'cat'
use workspace path inside the container, else environment variable like $WORKSPACE will be not in sync
don't quote environment variable value
fix launcher command overload