add chefspec for cookbook testing
change name of cookbook to chef-ec2-ami-tools to play nicer with chefspec
add spec for installing unzip
add spec for downloading ec2-ami-tools.zip
make an attribute for install_target
set EC2_HOME environment variable and add ec2-ami-tools/bin to PATH
use 0755 instead of 755 for file permission
Merge pull request #1 from anujbiyani/set_env_vars

Set env vars