added --save-dev

added save-dev flag to
Merge pull request #66 from lvnilesh/patch-1

added --save-dev
Merge @dannycoates addition of an 'ami' property to over-ride the default AMI.  Love it, serve yourself.
improved handling of env vars which provide aws ID and SECRET
upgrade to new AMI with latest security updates pre-applied
bump version
Pass user data from the command line
Merge pull request #68 from spitimage/master

Pass user data from the command line