Fix error in pathing for knife.rb and client.pem

[stephenlauck]

fixes issue where build node get's a knife.rb that looks like this:

[root@build workspace]# cat .chef/knife.rb 
node_name                "build.services.com"
log_level                :info
log_location             STDOUT
validation_client_name   "delivery-validator"
validation_key           "/etc/chef/delivery-validator.pem"
chef_server_url          "https://chef.services.com/organizations/delivery"
encrypted_data_bag_secret "/tmp/kitchen/encrypted_data_bag_secret"
trusted_certs_dir         "/etc/chef/trusted_certs"

node_name 'delivery'
log_location 'STDOUT'
client_key '/var/opt/delivery/workspace/.chef/knife.rb/delivery.pem'
trusted_certs_dir '/etc/chef/trusted_certs'

[ncerny]

@stephenlauck - Did you test to make sure this is working as intended? I'd like to merge it in if it is.