packer 0.6.1

Closes #136.
Closes #133.
Closes #130.
Closes #121.
Closes #120.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
Update README
Merge branch 'master' of https://github.com/Homebrew/homebrew-binary

* 'master' of https://github.com/Homebrew/homebrew-binary:
  Update README
  packer 0.6.1