reimplemented accepting extension EULA

- fixed displaying EULA translations (bnc#880504)
- fixed inconsistent layout (bnc#878976)
- keep the downloaded translations, do not store them to disk
changes

- 3.1.61
log not matching license files
use rspec 2.14.x at travis
Merge pull request #89 from yast/extension_eula

Reimplemented accepting EULA
upgrade: copy the old credentials, re-register the base product
call the product upgrade API function at SLE11 upgrade
backup and remove the old repository setup at upgrade
use timestamp in backup file name

to avoid possible rewriting an old backup
added comments