modified page.rb to parse amazon date correctly

When the amazon date was being parsed, it was using the %m/%d/%Y formatting option for the initial format.  Since the amazon format on the page is mm/dd/yy, upon formatting, the date was being set as 00yy-mm-dd since a century was not specified.  I changed the initial format to %m/%d/%y.  The date is now being set as yyyy-mm-dd.