Fixing issues with module names not being properly resolved in FilenamesResource

I was experiencing issues in my travis build process (but not locally - even when following through the travis build process locally) with module names in my `paths` config not being resolved to file names.

For example:

`jquery: "@AcmeCoreBundle/Resources/public/js/vendor/jquery/jquery"`

was not being resolved correctly to the full file path in `isFresh()` in `Factory/Resource/FilenamesResource.php`.

I've updated the logic for this. There's also a fix in there for when a `path` value points to a directory and not a real file.