Fixed aborting from the initial registration dialog

- Abortin needs to be confirmed (bnc#886662)
Version and changes
Merge pull request #151 from kobliha/one-more-abort-confirmation-to-fix

Fixed aborting from the base product registration dialog in installation
save the registration settings to autoinst.xml (bnc#892449)

at the end of installation
decrease vertical spacing in text mode (bnc#892747)

the main dialog did not fit 80x25 text screen
small refactoring in discover_registration_services.rb
small refactoring in local_server_dialog
small refactoring in import_certificate_dialog
changes