added --virtualization-type optional parameter which feeds into register-image awscli call at the end of the script
--kernel-id only set if virtualization_type is NOT hvm
fixed device mapping issue for hvm instances
adding grub patching and installation (needs to be done only if hvm is set, but for now lets just add it and get it working)
if building an hvm ami: patch grub-install for xen device names, install grub, fix device.map, ..., profit
create-ami.sh now prints out its args before executing, for debugging
reformat register-image command
Check ami_name for length
patch is required (sadly)
Don't rely on external source for diff
Only patch grub-install once

Make this script more re-run-able
Who knows what black magic has been performed on this volume previously!
Normalize reference to ${block_dev}1
fixup 676a4e8a4cbb01da10d18f7733cfe0a5b8f394cd
fixup 64881ed83e5e767adfedc4802deecf3a4721c340
Comments and hvm root device name

Per the block-device-mappings.html doc.
Merge branch 'docs_n_tweaks' into bsdmaster
Bail if AMI with same name already exists
CentOS 7 prep

* Replace sfdisk with parted
* also generate some json
Add utility scripts for building images in Docker

This allows for building images for distributions regardless of the
host you're building them on.