[py] Make the default version 3 for CM 4.5
[py] Make the default version 3 for CM 4.5

cdapio/cm_api,justinhayes/cm_api,justinhayes/cm_api,cdapio/cm_api,cloudera/cm_api,justinhayes/cm_api,cloudera/cm_api,cdapio/cm_api,cdapio/cm_api,cloudera/cm_api