Mock NationBuilder's events for development environment

[ben-pr-p]

Right now, running the code locally produces

[info] JOIN events to Core.EventsChannel
  Transport:  Phoenix.Transports.WebSocket
  Parameters: %{}
[info] Replied events :ok
[error] GenServer #PID<0.512.0> terminating
** (Protocol.UndefinedError) protocol Enumerable not implemented for nil. This protocol is implemented for: DBConnection.PrepareStream, DBConnection.Stream, Date.Range, Ecto.Adapters.SQL.Stream, File.Stream, Flow, Function, GenEvent.Stream, HashDict, HashSet, IO.Stream, List, Map, MapSet, Postgrex.Stream, Range, Stream, Timex.Interval
    (elixir) lib/enum.ex:1: Enumerable.impl_for!/1
    (elixir) lib/enum.ex:116: Enumerable.reduce/3
    (elixir) lib/enum.ex:1832: Enum.map/2
    (core) web/channels/events_channel.ex:19: Core.EventsChannel.handle_in/3
    (phoenix) lib/phoenix/channel/server.ex:226: anonymous fn/4 in Phoenix.Channel.Server.handle_info/2
    (stdlib) gen_server.erl:616: :gen_server.try_dispatch/4
    (stdlib) gen_server.erl:686: :gen_server.handle_msg/6
    (stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3
Last message: %Phoenix.Socket.Message{event: "ready", payload: %{}, ref: "34", topic: "events"}
State: %Phoenix.Socket{assigns: %{}, channel: Core.EventsChannel, channel_pid: #PID<0.512.0>, endpoint: Core.Endpoint, handler: Core.UserSocket, id: nil, joined: true, pubsub_server: Core.PubSub, ref: nil, serializer: Phoenix.Transports.WebSocketSerializer, topic: "events", transport: Phoenix.Transports.WebSocket, transport_name: :websocket, transport_pid: #PID<0.479.0>}

which is an error produced by trying to fetch events from the staging Nation Builder.

Fix options include:
– Reading events from a local cache when MIX_ENV=dev
– Giving the staging environment a read only api key for the production nationbuilder
– Setting up the staging nationbuilder to have events, which would unforunately require the login which we do not have.

Local cache solution can come first