cli: add config option
cli: add config option

a configuration file could be specify through --config option
this option could be useful to run functional and integration tests

Signed-off-by: Julio Montes <4a43a13347431ef00be7d745d08a5ba1757e840b@intel.com>

clearcontainers/runtime,clearcontainers/runtime,devimc/runtime,chavafg/runtime,devimc/runtime,chavafg/runtime,gorozco1/runtime,gorozco1/runtime