[ru] Replace all horizontal bar characters with em-dashes
[ru] chapter 6: Incorporate changes from commit a96c65b9ac

"Make 'Splitting a Commit' paragraph 2 more clear."
[ru] chapter 1: Incorporate changes from commit ccffb46d68

"Fix confusion between changes and revisions."
[ru] chapter 4: Update the translation of the Gitolite section
[ru] chapter 5: Translate images.
Merge pull request #375 from GArik/RU

[ru] Translation update + some more translated images