number of pages in downloadscripts

[kasper93]

Now there is 2698 pages on userscripts.org but downloadscripts.java have hard coded 1500 and after that it stops downloading, so I think it should be changed. (see https://github.com/skrul/greasefire/blob/master/java/greasefire-scraper/src/com/skrul/greasefire/DownloadScripts.java#L54)