git-svn: replace URL escapes with canonicalization

git-svn: replace URL escapes with canonicalization

The old hand-rolled URL escape functions were inferior to
canonicalization functions.

Continuing to move towards getting everything canonicalizing the same way.

* Git::SVN->init_remote_config and Git::SVN::Ra->minimize_url both
  have to canonicalize the same way else init_remote_config
  will incorrectly think they're different URLs causing
  t9107-git-svn-migrate.sh to fail.

[ew: commit title]

Signed-off-by: Eric Wong <normalperson@yhbt.net>