Build plugin staticDirs

- route `/plugins` -> `build/public/plugins`
- symlink `staticDirs` directories into `build/public/plugins`
- remove custom `/plugins` route handling

src/file.js

@@ -110,4 +110,9 @@ file.link = function link(filePath, destPath, cb) {
 	}
 };
 
+file.linkDirs = function linkDirs(sourceDir, destDir, callback) {
+	var type = (process.platform === 'win32') ? 'junction' : 'dir';
+	fs.symlink(sourceDir, destDir, type, callback);
+};
+
 module.exports = file;