git-svn simple introduction

git-svn:

1. set up your Git repo
   git svn clone http://svn.example.com/project/trunk
2. while being online, commit your changes to SVN;
   before going offline, do a git svn rebase to get your Git repo in sync with the SVN repo
3. while being offline, commit to the Git repo using git commit
   when getting back online again, do a git svn dcommit to push your changes back to the SVN repo