provisioners/chef-client: delete correct client

The server URL was being passed through rather than the client name.

Updated SSH package is supposed to be able to detect remote connection
closes now, which is nice.

Added ssh_host variable to vmware iso builder

core: Replace Gob RPC with MsgPack RPC

Conflicts:
	builder/amazon/common/ssh.go
	builder/digitalocean/ssh.go
	builder/googlecompute/ssh.go
	builder/openstack/ssh.go
	communicator/ssh/communicator_test.go
	communicator/ssh/keychain.go
	communicator/ssh/keychain_test.go

Fix unknown command and syntax error of the ESX5Driver, see #1012, #1015

provisioner/chef-client: validation_client_name

builder/googlecompute: configure instance name

Retain the current default of an instance name generated by UUID, but allow
users to choose a specific one. Useful for provisioning with Puppet when a
node name is used to select the right manifest.

Ensure parent directories are created for base boxes, fixes #1059