Refactor old migration creation snippet and an alternative one

snippets/ruby.snippets

@@ -896,16 +896,21 @@ snippet mct
 	create_table :${1:table_name} do |t|
 		${2}
 	end
-snippet migration
+snippet migration class .. < ActiveRecord::Migration .. def up .. def down .. end
 	class ${1:class_name} < ActiveRecord::Migration
-		def self.up
+		def up
 			${2}
 		end
 
-		def self.down
+		def down
+		end
+	end
+snippet migration class .. < ActiveRecord::Migration .. def change .. end
+	class ${1:class_name} < ActiveRecord::Migration
+		def change
+			${2}
 		end
 	end
-
 snippet trc
 	t.remove :${1:column}
 snippet tre
@@ -913,7 +918,6 @@ snippet tre
 	${3}
 snippet tref
 	t.references :${1:model}
-
 #rspec
 snippet it
 	it "${1:spec_name}" do