Look for file inside of provided dir.

I'll confess that I wasn't able to test this thoroughly b/c I'm stuck on an unrelated:

```
Error in get(name, envir = asNamespace(pkg), inherits = FALSE) : 
  object 'attach_dependency' not found
```

Is there a particular branch of Shiny I need to be running? I'm just trying to get this up so I can start testing the Shiny Server integration.