Merge branch 'ap/svn'

* ap/svn:
git-svn: add test for --add-author-from and --use-log-author
git-svn: add documentation for --add-author-from option.
git-svn: Add --add-author-from option.
git-svn: add documentation for --use-log-author option.

diff --cc Documentation/git-svn.txt
Simple merge

diff --cc git-svn.perl
Simple merge