[patch] admin shortcuts don't honor existing http:// absolute urls

[hugo]

When you have objects in your model that return serverabsolute urls with leading ​http://, they aren't honored by the current r/ shortcut view - it still prepends the site. The attached patch honors those URLs and if it starts with ​http:// (should maybe extended to ​https://, too?), it just returns the URL without attaching some site stuff.

I use a ​http:// carrying URL in one of my models where objects in the database return a get_<field>_url() result as their absolute url, because they are just media files listed in the database.

[hugo]

fixes admin shortcuts to honor leading ​http://

[Adrian Holovaty]

(In [903]) Fixed #634 -- Changed shortcut view to accept get_absolute_url()s that return URLs starting with http. Thanks, Hugo