Adds an optional config section to the help ouput for bundles

[mpeck]

This adds an optional config section to the help output for bundles. The section contains notes and a list of env vars. Both notes and env vars are optional.

Note that I didn't add the config section info to the bundle version model. I'm just pulling straight from the config file in the template. Since the data was already available in the config file and it's not used anywhere else right now, I figured that was the easiest solution.

Example config.yaml excert:

...
config:
  notes:
    The cfn bundle makes use of CloudFormation stack templates and stack policies that are
    defined in JSON documents and stored in pre-defined S3 locations. These locations are
    defined with the 'CFN_TEMPLATE_URL' and 'CFN_POLICY_URL' configuration variables.
  env:
    - var: AWS_REGION
    - var: AWS_ACCESS_KEY_ID
    - var: AWS_SECRET_ACCESS_KEY
    - var: AWS_STS_ROLE_ARN
      description: STS role ARN that should be assumed. Defined as 'arn:aws:iam::<account_number>:role/<role_name>'.
    - var: CFN_TEMPLATE_URL
      description: S3 Location of your stack templates. Defined as 's3://<bucket>/<path>'.
    - var: CFN_POLICY_URL
      description: S3 Location of your stack policies. Defined as 's3://<bucket>/<path>'.
...

Help output:

resolves #948
depends on operable/spanner#77

[vanstee]

This feels a little weird. I know we don't have a db column for this stuff, but it'd still be nice if we rendered it all as if it was one.

[mpeck]

I'm not sure I understand. Are you saying that we should add virtual fields for the config bits? I don't think that would change the test here, would it?

[vanstee]

Oh I think I misunderstood what was going on here. But it still seems weird that we need access to the config_file in the template. I'd be happier if we rendered the config key in the json as if it was a normal model attribute. This is probably fine though.

[vanstee]

Since config is typically "set and forget" I think it should probably go near the bottom. Maybe just above the homepage and author.

[mpeck]

That's actually why I put it at the top. I was thinking that the most important stuff was the command bits and I didn't want them to get pushed off the screen.