[backend] publisher: implement packtrack data caching
[dist] require new build script for package tracking
[api] fix product index handling

introduce one product into fixtures
[api] do not re-create, but update product index
[ci] do not destroy fixture data without proper restauration
[webui][api] Refactor attributes
[api] make sure we throw the right error for invalid users
[api] also accept verifymd5 for lastsuccess calls
[backend] map project name in <releasetarget> to remote
[api] allow engines not in our git to be loaded

They need to drop a file in lib/engines which requires the engine and
implements mount_it call