Define ruleset for major and minor change in data dictionary

[edsu7]

Major:

- breaking changes

Minor

- must be backwards compatible within major versions
- adding values to enum list
- add new field

Proposal

We will store base, extensionn and custom schema versions in lectern.
we will indicate the versions in a meta field:

meta: {
  baseVersion: "1.0",
  extensionSchemaVersion: "1.0",
  extensionSchemaURL: "www.github.com/xxx",
  customSchemaVersion: "1.0"
}

The custom version doesn't depend on the base or extension version, the base can be 4.4, extension can be 2.1, but the custom should always start with 1.0.