Allow connection timeout to be configurable

Right now the ClientConfigurationImpl.getConnectionTimeout is hard coded to 5000ms. I saw that master has it changed to allow that to be passed in from the ModelControllerClient.Factory but the new create method isn't used by the CLI classes.

It would be really nice if I could set a system property like the DEFAULT_MAX_THREADS option. That way I could set it as part of my maven options as well so the Cargo plugin would pick up the extra time too.

The reason for this request is that I am experiencing problems with Oracle JDK 7 on Mac OS X because it takes 5 seconds for the SSLContext.createSSLEngine to complete. It works with JDK 6 but it would be nice to start moving away from JDK 6 as a dependency.