Source opkg custom feeds

Users can add any additional repository to /etc/opkg/customfeeds.conf.
This would result in opkg being able install packages from that feed,
but updater would remove then as they would be missing.
2 jobs for opkg-feeds in 10 minutes and 50 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Test
passed test #7978

00:10:48

passed test_busybox #7979

00:10:50