Handling relative paths

Handling relative paths when loopback's server.js file is run from different directory than the project.

lib/providers/filesystem/index.js

@@ -29,6 +29,9 @@ module.exports.createClient = function(options) {
 
 function FileSystemProvider(options) {
   options = options || {};
+  if (!path.isAbsolute(options.root)) {
+    options.root = path.join(path.dirname(require.main.filename), options.root);
+  }
   this.root = options.root;
   var exists = fs.existsSync(this.root);
   if (!exists) {