traverseTree should work when a regular file is passed in

[mbieser]

Robustness enhancement.
Should work when passed the path to a regular (non-directory) file:

fs.traverseTreeSync('/home/vagrant/projs/api-core-js/package.json', function(path) { console.log(path);},function(path) { console.log(path);} );
undefined

Works fine when given a directory.

fs.traverseTreeSync('/home/vagrant/projs/api-core-js/', function(path) { console.log(path);},function(path) { console.log(path);} );
/home/vagrant/projs/api-core-js/.git
/home/vagrant/projs/api-core-js/.gitignore
/home/vagrant/projs/api-core-js/.ib_meta
/home/vagrant/projs/api-core-js/Makefile
/home/vagrant/projs/api-core-js/docker
/home/vagrant/projs/api-core-js/lib
/home/vagrant/projs/api-core-js/log
/home/vagrant/projs/api-core-js/node_modules
/home/vagrant/projs/api-core-js/package.json
/home/vagrant/projs/api-core-js/scratch
/home/vagrant/projs/api-core-js/test
undefined