Created a datalogging example & *.tsv to .gitignore

The datalogging example logs the meditation and attention data into an easy to read .tsv file with fields:

```tsv
unix_epoch_time meditation_data  attention_data ymd hms
```

Combined with a time record of daily activities it might yield interesting data.

Also, added *.tsv entry to the .gitignore to prevent cluttering with datasets.