git-svn: allow metadata options to be specified with 'init' and 'clone'
Since the options that affect the way metadata is handled in
git-svn, should be consistently set/unset throughout history
imported by git-svn; it makes sense to allow the user to set
certain options from the command-line that will write to the
config file when initially creating the repository.
Also, fix some formatting issues while we're updating
documentation.