use GardenRunner.Start to start the garden process
use GardenRunner.Start to start the garden process

- GardenRunner removed the start check for `garden.started` in the log
lines. We switch to use the Start method instead in order to ensure the
garden server is up and running prior to sending requests to it.

Signed-off-by: Sunjay Bhatia <df2d57be7987a471915f625a5499155bc16d4200@pivotal.io>

cloudfoundry-incubator/inigo