Support multiple repos, custom image srcs, encrypted AMI's, various fixes

[stonith]

• add default chef settings chef_repo_path and data_bag_path (depends on Mutiple cookbook and databag paths dalehamel/chefdepartie#1)
• add a hash prefix to cache.dat path. Currently a single cache dir is used and therefore mutiple repos would get mixed up
• added linecook.local domain suffix. This is to allow easier filtering of DNS lookups
• use config settings for image profile instead of hardcoded to :public. This allows for using s3 or custom sources for image downloads
• added encrypted AMI option. The enables the encrypted flag on the created AWS EBS volume. NOTE: this will prevent sharing AMI's publicly or between accounts
• added option to specify a custom bootstrap.erb instead of the included one (depends on Custom bootstrap template dalehamel/chef-provisioner#3)
  -allow chef-provisioner > 0.1.4 and chefdepartie > 0.1.1
• silence grub installer. With some images, grub would prompt to choose which disk to install on
• add option -a for bake command to allow for AMI creation. This does not assume --upload

[methodmissing]

🚢

[stonith]

@dalehamel this should be good for review.