Fixed #17455 -- Extended `CachedStaticFilesStorage` slightly to handle some URLs better that are used to add support for webfonts to IE 6-8. Also ignore `data:` URLs and fragment-only URLs (e.g. `#default#VML`).

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17282 bcc190cf-cafb-0310-a4f2-bffc1f526a37