Recipe checker

The idea is to ask recipe author to run this checker before submitting the PR (see the info document I added).

Here is the example output (we need to fix them).

```
% test/check-recipe.el recipes/*.rcp
`flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
`flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
Error in recipes/ac-R.rcp
* Use `:type github' for github type recipe
1 error(s) found.

Error in recipes/cmake-mode.rcp
* Property :before is for user.  Use :prepare instead.
1 error(s) found.

Error in recipes/durendal.rcp
* Use `:type github' for github type recipe
1 error(s) found.

Error in recipes/flymake-html-validator.rcp
* Use `:type github' for github type recipe
* WARNING: Are you sure you need features?
  If this library has `;;;###autoload' comment (a.k.a autoload cookie),
  you don't need `:features'.
1 error(s) found.

Error in recipes/highlight-indentation.rcp
* Use `:type github' for github type recipe
1 error(s) found.

Error in recipes/hl-tags-mode.rcp
* Use `:type github' for github type recipe
* WARNING: Are you sure you need features?
  If this library has `;;;###autoload' comment (a.k.a autoload cookie),
  you don't need `:features'.
1 error(s) found.

Error in recipes/html5.rcp
* Use `:type github' for github type recipe
* WARNING: Are you sure you need features?
  If this library has `;;;###autoload' comment (a.k.a autoload cookie),
  you don't need `:features'.
1 error(s) found.

Error in recipes/ioccur.rcp
* Use `:type github' for github type recipe
* WARNING: Are you sure you need features?
  If this library has `;;;###autoload' comment (a.k.a autoload cookie),
  you don't need `:features'.
1 error(s) found.

Error in recipes/lua-mode.rcp
* Use `:type github' for github type recipe
1 error(s) found.

Error in recipes/markdown-mode.rcp
* Property :before is for user.  Use :prepare instead.
1 error(s) found.

Error in recipes/pony-mode.rcp
* Use `:type github' for github type recipe
1 error(s) found.

Error in recipes/shadow.rcp
* Use `:type github' for github type recipe
* WARNING: Are you sure you need features?
  If this library has `;;;###autoload' comment (a.k.a autoload cookie),
  you don't need `:features'.
1 error(s) found.

12 error(s) found in total.
````