Update communicator.go

If block ends in a return statement.  Personal preference. It's less explicit, but more concise to drop the else and outdent the return.
Add 'security_groups' and 'subnets' args to 'aws_elb'
Implement specification of AWS security groups in ingress rules as <owner>/<id>
add vpc dns attribute support
config: HCL loader
terraform: register a type
providers/aws: fix RDB test syntax error
Fixes #179 -- expand ~'s in the path to a key file
Added a test and fixed a typo
Added a second test for the other form of tilde paths
config: use new HCL lib and structure
config: only walk if non-nil
Document that variable files can also be JSON, and clarify that terraform.tfvars is searched for in the *current* directory
helper/schema: initial work
Ports Packer code to load CLI configuration and external plugins
Clarifies that what failed loading is the CLI configuration as opposed to Terraform TF files
helper/schema: start the Diff function
helper/schema: Bools and ints can decode
helper/schema: diff-ing lists at a basic level
helper/schema: list ForceNew