When deleting a previously deleted model, returns and do nothing

	modified:   CHANGELOG.md
	modified:   lib/rails/generators/migration.rb
	modified:   test/generators/model_generator_test.rb
Merge branch 'railties_migrations_delete_already_removed_migration' of github.com:oliveiraethales/rails into railties_migrations_delete_already_removed_migration

Conflicts:
	railties/CHANGELOG.md
	railties/lib/rails/generators/migration.rb
	railties/test/generators/model_generator_test.rb