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/20180628142835_revert_alter_event_timestamps.exs

@@ -3,15 +3,15 @@ defmodule Mobilizon.Repo.Migrations.RevertAlterEventTimestampsToDateTimeWithTime
 
   def up do
     alter table(:events) do
-      modify :inserted_at, :timestamptz
-      modify :updated_at, :timestamptz
+      modify(:inserted_at, :timestamptz)
+      modify(:updated_at, :timestamptz)
     end
   end
 
   def down do
     alter table(:events) do
-      modify :inserted_at, :utc_datetime
-      modify :updated_at, :utc_datetime
+      modify(:inserted_at, :utc_datetime)
+      modify(:updated_at, :utc_datetime)
     end
   end
 end