[backend] do not use xrpc_setchanged for linked packages

setchanged uses an unfair unshift to bring the prps to the front.
[api] fix more of my stupid copy&paste programming

Unfortunately build status is hard to test during test suite as we don't build ;(
[api] make sure Event::Base.not_in_queue is quick
[api] fix fixtures, define issues from real source and rescan all sources after fixtures setup.
[backend] improve/cleanup linked package handling a bit
[backend] refactor putprojectconfig a bit
[api] remove deprecated calls during seeding

also add a dummy patchinfo where adrian's commit expects it, but it's
not the content the issue tests expect. But at least it's possible to
start the test suite now and only the tests affected fail not all
[api] fix seeds on empty database
[api] commit forgotten patchinfo file
[webui] make use of configured values in api actually.
[webui] disable broken-by-design test case. open github issue 408 instead
[backend] support "cannot build this repository" badhost
[backend] support "cannot build anything" worker answer
[api] fix combined issues searches, this avoids to show patchinfo files with open issues which are not assigned to a certain user who has a already closed issue in same patchinfo
[backend] no_proxy and repository download_url shall also be configured via configuration.xml
[api] fix variable name in status/history
[backend] distribute configuration
[api] make /about public available. it is used for live checks and is a route causing minimal load.
[backend] generate configuration events for schedulers and publisher
[dist] add fat kernel module to VM build workers