Refactor ReactionCore.registerPackage schema

[aaronjudd]

Refactor the ReactionCore.registerPackage package schema to be more structured.
Only registry is to be published to general client, while others (settings,permissions) would be published when admin.

ReactionCore.registerPackage
  name: 'reaction-paypal' # usually same as meteor package
  autoEnable: false # auto-enable in dashboard
  settings: # private package settings config (blackbox)
    mode: false
    client_id: ''
    client_secret: ''
  registry: [
    # all options except route and template
    # are used to describe the
    # dashboard 'app card'.
    {
      provides: 'dashboard'
      label: 'PayPal'
      description: 'Accept PayPal payments'
      icon: 'fa fa-paypal'
      priority: '2'
      group: 'paypal'
    }
    # configures settings link for app card
    # use 'group' to link to dashboard card
    {
      route: 'paypal'
      provides: 'settings'
      group: 'paypal'
    }
    # configures template for checkout
    # paymentMethod dynamic template
    {
      template: 'paypalPaymentForm'
      provides: 'paymentMethod'
    }
  ]
  # array of permission objects
  permissions: [
    {
      label: 'Pay Pal'
      permission: 'dashboard/payments'
      group: 'Shop Settings'
    }
  ]

I'd like to attempt to resolve #53, #308, #178, #136, #245 as well in this refactor.