Added safer path handling for Windows

sass.js

 var binding;
 var fs = require('fs');
+var path = require('path');
 try {
   if (fs.realpathSync(__dirname + '/build')) {
     // use the build version if it exists
@@ -63,11 +64,11 @@ exports.render = function(options) {
   options.error = options.error || function(){};
 
   if (options.file !== undefined && options.file !== null) {
-    return binding.renderFile(options.file, options.success, options.error, newOptions.paths.join(':'), newOptions.style, newOptions.comments);
+    return binding.renderFile(options.file, options.success, options.error, newOptions.paths.join(path.delimiter), newOptions.style, newOptions.comments);
   }
 
   //Assume data is present if file is not. binding/libsass will tell the user otherwise!
-  return binding.render(options.data, options.success, options.error, newOptions.paths.join(":"), newOptions.style);
+  return binding.render(options.data, options.success, options.error, newOptions.paths.join(path.delimiter), newOptions.style);
 };
 
 exports.renderSync = function(options) {

test/cli.js

@@ -62,9 +62,9 @@ describe('cli', function() {
 
   it('should compile with --include-path option', function(done){
     var emitter = cli([
-      '--include-path', __dirname + '/lib',
-      '--include-path', __dirname + '/functions',
-      __dirname + '/include_path.scss'
+      '--include-path', path.join(__dirname, '/lib'),
+      '--include-path', path.join(__dirname, '/functions'),
+      path.join(__dirname, '/include_path.scss')
     ]);
     emitter.on('error', done);
     emitter.on('render', function(css){