Logging transaction status right before installation

- bnc#875350: Making sure that readable log with transaction
  exists (called righr before installation starts)
Added testcase (libzypp data source)
Changes and version
Easier searching for begin/end of the transaction log
Enhanced checking in test
It must be already too perfect now :)
Merge pull request #46 from kobliha/log_user_selection_before_installation

Log user selection before installation