We should always merge option with the default
We should always merge option with the default

If the user doesn't provide any options file then we should just use the
generated default. If the user provides an options file then we should
merge it with the generated defaults.

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