renamed function
allowed for localization of ajax error message
jQuery 'load' not firing, need to use 'ready' instead

'get_cart' action was never being executed because the jquery 'load'
event would never fire.  This caused the 'loading...' message to remain
on the cart whenever caching is enabled.  The 'load' event was used for
other actions also, these were also changed to use 'ready'