Use ERB with ec2_config
Use ERB with ec2_config

It would be nice if we could use Ruby to set YAML keys with a default value. For example:


config/ec2.yml
```
project_tag: <%= ENV['CAP_EC2_TAG'] || 'project_name' %>
```

This way, if `CAP_EC2_TAG` is not set, then `cap-ec2` will default to using project_name for the `project_tag`.
forward3d/cap-ec2