don't need to monkey patch in to Capistrano::TaskEnhancements

hello!

You don't need to monkey patch into `Capistrano::TaskEnhancements` - you can extend the DSL like so:

```ruby
module Capistrano
  module DSL
    module Ec2

      def ec2_handler
        @ec2_handler ||= CapEC2::EC2Handler.new(env.fetch(:ec2_config, "config/ec2.yml"))
      end

      ...

    end
  end
end

self.extend Capistrano::DSL::Ec2
```