Merge git://git.bogomips.org/git-svn

* git://git.bogomips.org/git-svn: git-svn: Warn about changing default for --prefix in Git v2.0 Documentation/git-svn: Promote the use of --prefix in docs + examples git-svn.txt: elaborate on rev_map files git-svn.txt: replace .git with $GIT_DIR git-svn.txt: reword description of gc command git-svn.txt: fix AsciiDoc formatting error git-svn: fix signed commit parsing