Clones repositories without killing the schedulers ;)

- fix product converter cleanup

  usecase:
  <sometag>
    <disable repository="foo" />
    <enable />
  </sometag>
  if enabled is invoked with repoid="foo" the result is 0
  instead of 1. If there's a enabled and disabled tag with the same "exactness" 1 is returned.
- This issue raised up in #487400.

* make it easier to hit the links and not hitting "remove" cross
  unintentionally

  package update (bnc#486053).

  This helps to simplify package dependencies.

- moved remote project finder into DbProject model
- pass metadata requests for remote projects/packages to backend

- support 'repairlink'
- support 'lastworking' link query

  * a maintainer can be deleted as long as there's still another maintainer for a project/package
  * bugowners can be always deleted - it doesn't harm if a project/package has no bugowner
- fixes #444660: "Can't delete bugowner via webclient"

Proj:/ect

- fix for #479547 and #345429: if no repos are defined and trigger rebuild is issued fail with a nice error and redirect to add_target_simple