New criterion for updates.img using

[Petr Schindler]

I propose new beta criterion: 

"The installer must be able to use updates.img obtained by any supported way"

I think, that this should be at criteria too. There are test cases which uses this feature - [1], [2]

[1] https://fedoraproject.org/wiki/QA:Testcase_Anaconda_updates.img_via_installation_source
[2] https://fedoraproject.org/wiki/QA:Testcase_Anaconda_updates.img_via_local_media