[backend] export product release number to kiwi files if defined
[backend] avoid dispatching of copy/upload jobs
[backend] accept "0" also as product release
[api] increase diff timeout from 10=>30 seconds
[dist] Fix/Enhance obs_mirror_project

Add back obs_mirror_project script deleted in commit a91447c5af2869ed518f8934357e173bfd723005
and fix/enhance with the following:
1. Include 'optparse' to parse commandline options
2. Verify user inputs from commandline options
3. Handle existing file by comparing file size
4. Download retry up to 3 times in case temporary network interruption
[backend] Move 4 bs_worker config options into BSConfig.pm

1. buildlog_maxsize
2. buildlog_maxidle
3. xenstore_maxsize
4. gettimeout
[backend] add interface to report back the job status
[webui] show extra job status informations on build job page

- works also if worker broke down after getting the job
- gives a hint how long the job may still run
[api] one more possible accept error
[webui] some code improvements
[backend] make just the buildlog settings configurable
[webui] do not crash on invalid request accept
[api][backend][webui] fix route conflicts between /_status and /_jobstatus

document the _jobstatus api and add at least some very
basic tests for them.
[api] fix incorrect diffing on creation of submit requests with given target
[webui] Small fixes in the OBS specific markup

 * @user was not working at the very beginning of the comment.
 * Req# and SR# are now case insensitive (and Request# added)
[webui] catch some more exceptions to avoid 500 crashes in request handling
[api] handle diffing of new request to project linked targets correctly
[webui] avoid hanging live log page, when the worker allows TCP connect, but does not deliver data
[backend] enable caching of binaries when OBS instance is forwarding it for another instance.
[webui] do not crash when handling remote instance with invalid SSL CA

This happened when adding packman OBS instance and trying to add
a repository in the simple webui view.

Repository targets won't become visible anyway.