BUG: validator crashes if datapoint file contains empty line

if one of the datapoint files contains an empty line, validator would crash
datapackage creation would also crash

test like this

```
geo,time,indicator
afg,1989,12
afg,1990,13
afg,1991,14
```

```
geo,time,indicator
afg,1989,12
,,
afg,1990,13
afg,1991,14
```