Code review comment for ~johnguthrie/cloud-init:instance_hostname_subst_for_chef

Thank you again for this sensible suggestion. As mentioned in the above comment ([1]),
 we'll make sure to fold in the use cases suggested here into the general jinja templater for cloud-config modules in the branch at [2]. I'll mark as disapprove/rejected as the general templater should provide the template variable you requested, and much more. Thanks again for getting the ball rolling here.

This means you can provide your cloud-config with the following:

## template: jinja
#cloud-config
chef:
   node_name: {{ v1.instance_id|replace('i-', '') }}

references:
 [1]: https://code.launchpad.net/~johnguthrie/cloud-init/+git/cloud-init/+merge/331905/comments/875174
 [2] https://code.launchpad.net/~chad.smith/cloud-init/+git/cloud-init/+merge/334030