provisioner/ansible: more configuration options

builder/qemu: binary name to be configured

builder/qemu: handle reboots in the shell provisioner

builder/vmware: get host IP by creating & inspecting connection, allows hypervisor...

builder/googlecompute: save private key when debugging gce builder

builder/virtualbox/ovf: Add import_opts to the virtualbox-ovf builder. 

builder/amazon/instance: use --url flag rather than --location for ec2-upload-bundle

esx5, Get host IP by creating & inspecting connection, allows hypervisor to reside in other networks

have existing virtualbox virtual machines where I need to keep the mac
addresses so that the network interfaces come up when packer boots them.
Otherwise I just get SSH timeout and I'm unable to configure the machines.

Adding docs to #645 on the website

Setting `"ami_groups": ["all"]` will make the AMI publicly accessible.
Correcting website docs for this.

AWS docs (http://goo.gl/rNZiCs) show that --location is deprecated and
to use the --url flag and reference the region endpoint instead.

have existing virtualbox virtual machines where I need to keep the mac
addresses so that the network interfaces come up when packer boots them.
Otherwise I just get SSH timeout and I'm unable to configure the machines.

ansible looks for group and host vars directories as well as playbooks
this revision to the provisioner uploads those as well.
squashed to a single commit by strcrzy.

Signed-off-by: Prasanna Santhanam <tsp@qubole.com>

On some systems the default Qemu binary name of qemu-system-x86_64
isn't appropriate.  So expose the binary name as a configurable item,
allowing the user to set it to something more appropriate if they need
to.

allow users to provide a replacement command / extra args to the
ansible-local provisioner.

this is useful, for example, to unbuffer output when using the
docker builder, or to modify ansible behavior, like enabling
verbose mode, injecting variables, or changing paths.