Change models, new migrations, fix front and make tests work

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/eventos_web/views/participant_view.ex

@@ -0,0 +1,17 @@
+defmodule EventosWeb.ParticipantView do
+  use EventosWeb, :view
+  alias EventosWeb.ParticipantView
+
+  def render("index.json", %{participants: participants}) do
+    %{data: render_many(participants, ParticipantView, "participant.json")}
+  end
+
+  def render("show.json", %{participant: participant}) do
+    %{data: render_one(participant, ParticipantView, "participant.json")}
+  end
+
+  def render("participant.json", %{participant: participant}) do
+    %{id: participant.id,
+      role: participant.role}
+  end
+end