Fixed gradeable activity admin.
Squashed commit of the following:

commit 6799e5d77a7376c3cc49731cda6235f7104f1b6d
Author: Jacek Bzdak <jbzdak@gmail.com>
Date:   Thu Oct 31 21:54:18 2013 +0100

    Added compiled asset

commit e9792f4dc505b4006220371d49614c512ff9794b
Author: Jacek Bzdak <jbzdak@gmail.com>
Date:   Thu Oct 31 21:52:49 2013 +0100

    Poprawki do sprawdzania zadań.

commit 3db03e0aa8101faa1d67a731d366b913300dc693
Author: Jacek Bzdak <jbzdak@gmail.com>
Date:   Thu Oct 31 12:51:21 2013 +0100

    ...

commit d6b444bb416db664b1f8a8bc3f1c4ef471bc4123
Author: Jacek Bzdak <jbzdak@gmail.com>
Date:   Thu Oct 31 12:49:51 2013 +0100

    ...