Fix rss1 pub date

RSS1.0 Feeds such as http://www.debian.org/News/news were not having their article publication date correctly parsed. Hence all articles would continually be updated with a new publication date on every run of the crawler. The test on line 82 for 'if ($pubDate)' was not returning true as an empty SimpleXMLElement Object was being returned rather than the date string. This string coercion ensures the date is returned (eg. in the case of the above feed "2013-06-15") and thus the test will be true and therefore the $article->published will be set to $timestamp.
The same class file in the server has also been updated with the same correction.