markdown file not found

I ran `markdown-watch` in a directory with the target file, and then navigated to:

```
http://localhost:8080/file.mkd
```

I got a response back from the app that the file was not found, but I think the file should be there. As mentioned in the previous issue, I could browse the directory for markdown files, that could help clear this up:

```
  http://localhost:8080/
```
