Two wrapper scripts that find git and svn using the ENV variables we support and then searching through the PATH and looking inside Xcode.app if necessary.
Now just calling git or svn in Homebrew code will find and exec the right tool and we can stop fussing.
Apologies to @adamv who is probably unimpressed that the cmds directory has non-commands in it now. If it's consolation these are temporary pending some more work on superenv whereby some more directories are created under the superenv root.
