Ability to include policy files from other repos via GIT or URL reference

[jamesdadd-nomi]

Speaking with @deitch about this, we have a use-case where we would like to reference and include policy files from within the serverless.yml file.

These policy files would be located in a separate GitHub repo managed and blessed by the Security function, and we need to be able to reference them via:

• standard GIT pull
• general URL reference

Credentials will need to be considered, and the ability to include these as part of the include process.

[medikoo]

@jamesdadd-nomi thanks for this proposal. We're open for PR that delivers that!