Fix mix format and format migrations too

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

Fix credo warnings

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

Show elixir version

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

Also lint migrations

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

Reset allow failure to false

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

priv/repo/migrations/20180531162301_add_approved_status_to_member.exs

@@ -3,13 +3,13 @@ defmodule Mobilizon.Repo.Migrations.AddApprovedStatusToMember do
 
   def up do
     alter table(:members) do
-      add :approved, :boolean, default: true
+      add(:approved, :boolean, default: true)
     end
   end
 
   def down do
     alter table(:members) do
-      remove :approved
+      remove(:approved)
     end
   end
 end