Add FiNER dataset
Hi,

this PR adds "A Finnish News Corpus for Named Entity Recognition" as new `finer` dataset.

The dataset is described in [this paper](https://arxiv.org/abs/1908.04212). The data is publicly available in [this GitHub](https://github.com/mpsilfve/finer-data).

Notice: they provide two testsets. The additional test dataset taken from Wikipedia is named as "test_wikipedia" split.