Add rails-new.
Fix foo-mode-on functions descriptions in :prepare
Add :prepare blocks for some recipes

Add autoloads and/or foo-mode-on functions
 in :prepare block for:

- recipes/ace-jump-mode.rcp
- recipes/auto-indent-mode.rcp
- recipes/pp-c-l.rcp
- recipes/window-number.rcp
- recipes/windsize.rcp
Merge pull request #2003 from Pitometsu/pitometsu

Add :prepare blocks for yet more recipes