Do not use a custom path by default in Gemfile

I don't think that using a custom path by default is what users would expect when trying to use the project. 

I was trying to run the specs and got this error message.

```
The path `/Users/marcos/Proyectos/lotus/lotus-utils` does not exist.
```

That change should fix the problem. Should this be applied to other lotus projects or is this an error from my side?

Thanks!