Fix front-end, allow events to be created by a group, allow to get sessions from an event

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

lib/eventos/groups/groups.ex

@@ -37,6 +37,14 @@ defmodule Eventos.Groups do
   """
   def get_group!(id), do: Repo.get!(Group, id)
 
+  @doc """
+  Gets a single group, with all associations loaded.
+  """
+  def get_group_full!(id) do
+    group = Repo.get!(Group, id)
+    Repo.preload(group, [:members, :organized_events])
+  end
+
   @doc """
   Creates a group.