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.

Change the word `aws_access_key` to `aws_secret_key`.

website: update defaults for DO ID's

/cc @mmckeen

/cc @mmckeen - Did a refactor here, CC'd in case you're curious
or want to learn :)

common: set user agent in downloader

builder/virtualbox,vmware,qemu: add more special scancodes

provisioner/ansible: upload playbooks correctly

website: fix typo in qemu documentation

`Provision` calls uploadFile on each path in playbook_paths, but
playbook_paths can only contain directories, per bf7530ca28.

This changes `Provision` to call uploadDir instead.

Updating the googlecompute builder documentation.

Update post-processor.html.markdown

Fixed some typos in the interface{} mentions.

Update virtualbox-iso.html.markdown

Changed type to virtualbox-iso

Fixes #806 Build fails if GOPATH has multiple paths