web-mode: bump minimum Emacs to 23.1
web-mode: bump minimum Emacs to 23.1

For `:safe` keyword; see http://stackoverflow.com/a/5386504

Closes #571.

Signed-off-by: Alex Dunn <46952c1342d5ce1a4f5689855eda3c9064bca8f6@gmail.com>

Homebrew/homebrew-emacs