Use path.relative instead of manual string replacement.

Fixes Windows inconsistency (#26).

Author: domenic

lib/wrench.js

@@ -49,7 +49,7 @@ exports.readdirSyncRecursive = function(baseDir) {
 
     // convert absolute paths to relative
     var fileList = readdirSyncRecursive(baseDir).map(function(val){
-        return val.replace(baseDir + '/', '');
+        return _path.relative(baseDir, val);
     });
 
     return fileList;
@@ -106,7 +106,7 @@ exports.readdirRecursive = function(baseDir, fn) {
 
             fn(null, curFiles.map(function(val) {
                 // convert absolute paths to relative
-                return val.replace(baseDir + '/', '');
+                return _path.relative(baseDir, val);
             }));
 
             if (waitCount == 0) {