Adapt schemas to epochs and member exclusion

[Powersource]

For https://github.com/ssbc/ssb-tribes2/issues/73 and https://github.com/ssbc/ssb-tribes2/issues/68

• [x] Test exclude schema
• [x] Fix array schemas
• [x] Make sure definitions are imported always
• [x] Allow recps in init
• [x] Update readmes
• [x] split init schemas
• [x] update tests
• [x] update/create readmes

[Powersource]

Just ran into this

the fuck. so this apparently doesn't seem to work (we use it in some schema)

recps: {
  type: 'array',
  item: { $ref: '#/definitions/groupId' },
  minItems: 1,
  maxItems: 1
},

but this seems to work (which we also use in some places

recps: {
  type: 'array',
  items: [{ $ref: '#/definitions/groupId' }],
  minItems: 1,
  maxItems: 1
},

[Powersource]

published v6 now