Clear errors list if user decides to continue

 * Implemented by delegating ServiceManager.errors to ServiceManagerService
Fix last changelog entry by including the bnc
Some tests polishing
Merge pull request #81 from ancorgs/clean_error_messages

Clear errors list if user decides to continue
do not set runlevel while autoinstallation
packaging
adapt docu
Merge pull request #84 from yast/review_140728_default_target

[Review] Request from 'schubi2' @ 'yast/yast-services-manager/review_140728_default_target'