nuxeoctl should return error status on start failure

By default the launcher returns a 0 status code when some components are not deployed or when a server is already launched.

There is a --force option that returns -6 (bad configuration) when there is already a server running on the same port.
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Replacing the -force option by a -strict option and extend it so that

nuxeoctl --strict start

will abort with an error code when a component is not started or when there is a server already running.