[backend] add workerid and jobid verifiers for convenience

Use them in the repserver, also make workerid an optional extra
argument for all worker calls to ease debugging.
[api] fix product indexing
[api] basic tracking of CPE ids in products
[obs_mirror_project] add api-url to osc meta calls

Add api-url to the osc meta calls for prj and prjconf to make sure the openSUSE api is used.
If the openSUSE API is not the default one prj and prjconf are just empty created or overwritten with nothing.
[backend] drop old "run-on-server" mode, it was never used for real
[backend] support definition of updates in products for SLE12 style
[api] add product update repository tracking.
[api] add l1 support level to schema
[backend] Use rpm product provides instead of content lines for SLE 12 / openSUSE 13.2 media style
[api] test case showing the problem with issue 328
[api] refactor project#update_from_xml to make it more modular

The goal is to parse the repositories twice, once save only those
that work and then another pass to get the repos matching against it.

This of course opens the question how long should we do that - i.e.
how many levels of nested repos do we support, but I guess if we survived
with only one level so far, supporting two will do for another decade
[api] fix the case when more than two time re-usage of repositories in same project on initial creation (issue 328)
[backend] support definition of end-of-life time in products
[backend] SLE 12 medias require an end-of-life definition
[backend] repserver: fix import stripping in kiwi product buildinfo generation
[backend] dispatcher: fix endless loop when called with --restart

broken with commit #bf43b5c4, grrr
[api] support autocleanup of projects.

Can be enabled globally for ~:branches: projects.
Opt-in and Opt-out per project is possible by adding or removing the OBS:AutoCleanup attribute
[api] split the perform function for PCACR
[dist] add dispatch constraints features to release notes
[api] save the attribute too in clean up job