Add basic Event Stream struct

lib/hunter/event_stream.ex

@@ -0,0 +1,27 @@
+defmodule Hunter.EventStream do
+  @moduledoc """
+  Event stream is a simple stream of text data encoded using UTF-8
+
+  Messages in the event stream are separated by a pair of newline characters. A
+  colon as the first character of a line is in essence a comment, and is ignored.
+
+  ## Fields
+
+  * `id` - event id
+  * `event` - the event's type
+  * `data` - data field for the message, this data is JSON-encoded
+  * `retry` - re-connection time to use when attempting to send the event.
+
+  See: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#Event_stream_format
+
+  """
+
+  @type t :: %__MODULE__{
+      id: String.t,
+      event: String.t,
+      data: String.t,
+      retry: non_neg_integer
+  }
+
+  defstruct [:id, :event, :data, :retry]
+end