I18n ajaxify

The ajaxify.js has some hard-codded English texts that I replaced with i18n keys.
Since two of the texts were not exists in the locales I have added them in default.
Also in other out-of-box locales, I used the following format:
close_cart : close_cart_es

I have test them manually, but I am not sure if I need to write test for i18n fixes or not.
@cshold