Replace ListServers hack with update ServerById

[gophercloud#168](https://github.com/rackspace/gophercloud/issues/168) has been
patched to not panic on non-existing server id's. If an error is returned,
check if the error is a 404 first before bailing.

builder/openstack: Workaround for gophercloud.ServerById crashing [GH-1257]

Fix openstack ServerById crash

builder/amazon-common: Sort AMI strings before outputting [GH-1305]

Sort AMI names in Artifact.String - fixes random test failures

With go tip, the output from Artifact.String will sometimes be output in a
different order than the tests. Sort the AMI strings before outputting.
See https://travis-ci.org/mitchellh/packer/jobs/28748467 for an example of this
failure.

gophercloud.ServerById is broken in v0.1.0 - it will crash if you feed it a
non-existing server ID (see [rackspace/gophercloud #168](https://github.com/rackspace/gophercloud/issues/168))

Instead, list all servers and iterate over them. If the server id isn't found,
return "DELETED" as a state. Not perfect but it works until next version of
gophercloud is released.

Images link is 404, now must use API

Add gox installation instructions to Contributing

Resolves #1256, add warning mesasge to VMware ESXi driver

Update the qemu example 

builder/parallels: Fixed problems with character when typing boot command

[feature] Support boot command for pvm builder

Parallels-iso errors while removing floppy drive GH-1226

Parallels errors while creating floppy disk GH-1225

Properly escape security_group_id to avoid markdown interpretation of the '_'

Instead of pointing at a specific (in this case actually non-working!) revision, point to the github UI for the
head revision.
The user is expected to find the 'raw' link there, but the page allows to also quickly look at changes etc, which
might be helpful for people unfamiliar with kickstart files.

Use a single command line, avoid the graphical installer, and use {{ .HTTPIP }} rather than the actual IP.
Also wait a bit before entering the commands to increase the chance of actually being in the boot menu.

increase VMware cleanup timeout to 120 seconds

Add ability to configure networks for openstack

website: Don't use a real domain in examples.

Use example.com instead.

Force IPv4 addresses from address pools in Openstack. Fixes #1258

Add configuration option `networks`, a list of network UUIDs, to attach to the
source instance.

In some openstack installs, no default network will be attached or the network
with the ability to attach a public floating IP will need to be specified.

Rackspace defaults to a public IPv4 and IPv6 address. These are returned in
random order, with the sprintf further on generating an incorrect connection
string if on IPv6. Force IPv4 until support for correct connection strings and
a configuration flag for logging in over IPv6 is added.

vmware-vmx clarify VMware Fusion support