[dist] do not fail without sphinx db
[backend] repair import handling if the old full handling is used

It got broken with commit #80090475.
[backend] put '--directdepsend--' marker before prereqs

Newer perl-BSSolv will look for that marker.
[backend] only add directdepsend marker if we have prereqs
[api] do not crash when refering to a not existing repository
[api] improve readability
[api] store also binary build time in tracking
[backend] put 'medium' in packtrack data for isos/repos
[api] report also operation on binary release search results
[api] support binary release search for operation

and fix xpath syntax for disturl and supportstatus
[api] run some delayed jobs in special queues

* bug issue tracker job runs in extra queue to avoid that an external slow
  bugzilla server is slowin down processing all jobs
* binary tracker is doing heavy SQL load, so limit it to one job
[backend] fix media to medium attribute for product pool repos
[api] fix indenting the xml results of searches

Also, speed it up. Before, it rendered xml, to parse it, to render it again.
[api] do not crash on missing build time
[backend] allow to build 32bit big endian ppc on 64bit little endian host
[api] another place to avoid a crash when getting no build time
[api] store and render medium for binary tracking
[api] fix date of migration
[api] move binary release parser to proper model
[backend] support deletion of notificationpayload data