Description of problem:
See 441127 - PackageKit will keep re-downloading metadata until it gets the
right one like Yum does, however this can take lots of bandwidth and is
especially bad for users with bandwidth caps.

It would be great to have a "maximum # of failures" preference so that after X
failed downloads, it will just try again later.

Version-Release number of selected component (if applicable):
gnome-packagekit-0.1.11-1.fc9.x86_64

How reproducible:
Sometimes (depends on mirror syncs)

Steps to Reproduce:
1. Wait for PackageKit to refresh metadata
2. Observe bandwidth usage with a network monitor
  
Actual results:
Bandwidths will get high (800kbps) for a few seconds, drop to 0, then back up
again for several minutes as it tries another mirror.

Expected results:
Just an example, if the maximum failure count was 5 then after 5 bad mirrors it
would wait for them to sync (an hour or two?) then try again.