Add configuration to support CloudFront Restricted Views

[seang96]

I added an option to add additional restricted behaviors to directory paths in S3. This allows one to create generated content and host under their domain that needs to be restricted by CloudFront's signing of URL's or signing of cookies while keeping parts of the website public.

Below is an example of the new configurable variables.

custom:
  fullstack:
    restrictedPaths:
      - PathPattern: path/*
        TrustedSigners:
          - self

[andrewphahn]

Please add a section to the README documenting how and why to use this.

[andrewphahn]

This is something I have wanted to add for a long time. Thank you!