builder/amazon/all: AMI region copy fixes

Conflicts:
	packer/config_template.go

website: minor URL typo

URLs with special characters should escape them.

/cc @whostolebenfrog - I actually simplified things quite a bit. I added
a "uuid" global template function so it just uses that now. I renamed it
so that it is clear it is a temporary keypair.

builder/amazon/ebs: Allow customization of temporary ssh key name

builder/virtualbox: Add `hard_drive_interface` option

Defined in a template using ssh_keypair_pattern. Defaults to "packer %s"

Otherwise we get stuck in a long loop. Whoops.

See comment.

Most APIs return "has a pending event" but power off seems to return
"already a pending event". WTF. Also, just wtf at the DigitalOcean API.
I can't wait until they change their english and this breaks. Because
it is definitely going to happen, and it's going to be such a fun time.

/cc @pearkes - I hate this thing.