Preface and license translation
Introduction translated

And some small fixes added
Merge pull request #7 from Bakuutin/master

Preface and license translation
Translate appendix B - command line embedding
Merge pull request #5 from madhead/embedding_git

Translate appendix B - command line embedding
Translate appendix B - Libgit2
Merge pull request #8 from madhead/embedding_git

Translate appendix B - Libgit2
Translate appendix B - JGit
Translate 7.7 "Reset Demystified".
Translate 7.5 "Searching".
Apply feedback
Translate 7.5 "Searching": fix errors according with review.
About&History fixes
Merge pull request #9 from madhead/embedding_git

Translate appendix B - JGit
Translate 7.4 "Signing Your Work".
Merge pull request #12 from dmitry-krasilnikov/master

Исправления About и History
Basics partially translated
Translate appendix C
Merge pull request #13 from lyobzik/7.4-signing

Translate 7.4 "Signing Your Work".
Basics translation fixes