bolsonaro

- Add train_on_subset option to specify on which subset the model will be trained (either train or dev);
- find_dotenv() only working by specifying the example env on my machine?
- Add the seeds option to specify the seed(s) to use, and remove the use_random_seed, because it's obv if random_seed_number is used;
- Use a logger in train.py instead of prints.