this breaks using absolute paths. 

Say these files exist:
    ```/a/b/x.ini
    /a/c/y.ini```

if ```x.ini``` has ```+include /a/c/y.ini```, configman will try to load it as ```/a/b/a/c/x.ini```

a better solution would be to treat pathnames that begin with a "/" as absolute.  Only pathnames without the first "/" would be considered relative.

```                    
if not include_file.startswith('/'):
    include_file = os.path.join(
        original_path,
        include_file
     )
```