restore the original repository status in the installed system (bnc#899999)

reverted commit c9d4f55, fixed conflicts
changes

- 3.1.127
RepoState: method rename (restore_state -> restore)
finish_dialog_test.rb: reset instead of mocking
Merge pull request #173 from yast/revert_repository_changes

Enable Updates in installed system (bnc#899999)