Copy package.el as carton-package.el

wget http://repo.or.cz/w/emacs.git/blob_plain/1a0a666f941c99882093d7bd08ced15033bc3f0c:/lisp/emacs-lisp/package.el -O carton-package.el
Load carton-package.el as package.el in Emacs 23
Use destructuring-bind instead of pcase
Add smoke test
Run smoke test with Emacs 23 in Travis
Use expand-file-name instead of concat
Don't run "make elpa" with Emacs 23 in Travis CI