Revert "CLOUDSTACK-6940:Templates cannot be downloaded from URLs without"

This reverts commit 569e94908b6fa471f2f72578e1ff21f3fa7c6a4e.
Revert "CLOUDSTACK-7312:ISOs cannot be downloaded from URLs without matching"

This reverts commit 737f76df8c86666b47ba347ae46fc10d73b1fee6.
CLOUDSTACK-6940, CLOUDSTACK-7312, CLOUDSTACK-5512: Template/ISO/Volume
upload rejects some valid URL formats. Also consolidate URL format check
into one util routine.