[ADD] DCOS-1323 dcos help <subcommand> should be aliased to dcos <subcommand> --help
[ADD] DCOS-1323 dcos help <subcommand> should be aliased to dcos <subcommand> --help

sis-tools/dcos-cli,genome21/dcos-cli,mesosphere/dcos-cli,dcos/dcos-cli,dcos/dcos-cli,Yhgenomics/dcos-cli,dcos/dcos-cli,sis-tools/dcos-cli,dcos/dcos-cli,kensipe/dcos-cli,mesosphere/dcos-cli,kensipe/dcos-cli,Yhgenomics/dcos-cli,dcos/dcos-cli,kensipe/dcos-cli,genome21/dcos-cli,sis-tools/dcos-cli,mesosphere/dcos-cli,kensipe/dcos-cli,kensipe/dcos-cli