[api] improve multiple channel target error message
[api] channel definition in the incident source prefered
[api] support acceptinfo in maintenance release actions
[api] make "id" attribute obsolete in new product descriptions
[api] fix migration failure when updating directly from OBS 2.4, issue 648
[dist] add migration test during package build
[backend] product id attribute is obsolete for new products
[api] Extended testcase for releaserequests with comment
[webui] fix test for 3 groups now
[api] make it possible to subscribe to more comment events

Adding source_maintainer as receiver role for request comment events
[backend] allow an array reference as publish hook
[backend] require set release for SLE 12
[backend] use product release, not registered one
[backend] forbid the register release for SLE 12
[backend] fix product xml description
renderPackagesTable() function did ignore length parameter

This fix the issue, that package lists always first rendered with 25 items setting, ignoring
the given length parameter.

Signed-off-by: Karsten Keil <keil@b1-systems.de>
[test] remove illegal empty release field for register
[test] check for repo tag in repomd.xml data
[test] ensure that api configuration got written to the backend in test suite
[backend] follow release number change for SLE 12 media style medias

drop product related keys in content file