Disable web URL fields when repository is known
Disable web URL fields when repository is known

Some users seem to think it's necessary to clear these fields out when
they are auto-set. The most appropriate thing to do seems to be to
disable editing them if we know what their values should be.

Signed-off-by: Paul Eggleton <737d4dae46a541673d7bf4e0d5b32714b16528d8@linux.intel.com>

bartosh/layerindex-web,bartosh/layerindex-web,bartosh/layerindex-web