allow to login with email instead of nick as well + tests

db/migrate/20130920201529_allow_missing_nick.rb

@@ -0,0 +1,9 @@
+class AllowMissingNick < ActiveRecord::Migration
+  def self.up
+    change_column :users, :nick, :string, :default => nil, :null => true
+  end
+
+  def self.down
+    change_column :users, :nick, :string, :default => "", :null => false
+  end
+end