Add additional fields to <meta> section

[hacksalot]

Currently, meta defines just two properties, the FRESH schema version and the private resume version.

meta: {
  "format": "FRESH@1.0.0",
  "version": "0.1.0"
}

Add additional metadata as follows:

• The official endpoint of the latest inbound resume. This is the "single source of truth," expressed as a JSON or YML endpoint that can be parsed by HackMyResume and other tools.

• The official endpoint of the latest outbound resume. This is the most-canonical HTML (or other web-visible) format of the latest version of the resume; the URL that you'd hand to a random stranger on the subway. This may also be expressed as an array of URLs corresponding to specific resume formats.

• The official endpoint of the inbound resume repository. This is the git-addressable URL of the repository containing the user's resume JSON file(s). It provides context for the version field (versions can be pegged to concrete releases).

• Creation date and modified date.

And eventually....

• Localization info.

• For partial / merged resumes, a property specifying minimal but sufficient info to recreate the transformation.