adding configurable mtu of container interface
adding configurable mtu of container interface

tangfeixiong/garden,shashidharatd/garden-linux,savaki/garden,cloudfoundry-incubator/garden,shashidharatd/garden-linux,shashidharatd/garden-linux,tangfeixiong/garden,tsaleh/garden,cloudfoundry-incubator/garden,cloudfoundry-incubator/garden-linux,shashidharatd/garden-linux,cloudfoundry-incubator/garden-linux,tsaleh/garden,savaki/garden,cloudfoundry-incubator/garden-linux