Add a version check for DC/OS 1.13
Add a version check for DC/OS 1.13

This will have to be uncommented once DC/OS 1.13 is released. Afterwards
we're planning to have the latest CLI applicable for future versions of
DC/OS so he script won't have to be updated anymore.

dcos/dcos-cli,dcos/dcos-cli,kensipe/dcos-cli,dcos/dcos-cli,kensipe/dcos-cli,dcos/dcos-cli,kensipe/dcos-cli,kensipe/dcos-cli,kensipe/dcos-cli,dcos/dcos-cli