Fixed aborting while adding the add-on/extension

- bnc#886662
Changes and version
Fixed docu
Merge pull request #139 from kobliha/aborting-installation

Fixed aborting while adding the add-on/extension
better AY support
download addons
created AddonRegCodesDialog
store config
handle nil
refactoring - move code from client to lib
move from client to lib
move workflow code to a separate file
move from client to lib
require cleanup
better fingerprint handling
registration fixes
import SSL certificate in AutoYast
refactored SSL certificate handling
allow only new "expect" RSpec syntax in tests
move HTTP download code to registration/downloader

and share it (used in EulaDownloader and SslCertificate classes)