Fixed the description of the access_key property.
Fixed the description of the access_key property.

The following issue is fixed by this: https://github.com/lmars/packer-post-processor-vagrant-s3/issues/15
lmars/packer-post-processor-vagrant-s3,themalkolm/packer-post-processor-vagrant-upload,unifio/packer-post-processor-vagrant-s3