Closes #29 | Add dataset loader for IJELID

[ljvmiranda921]

Closes #29

Notes:

• IJELID is a token-level language identification task. I can't seem to find it in the supported tasks so I added a new one in this PR (b472a1c)

Checkbox

• Confirm that this PR is linked to the dataset issue.
• Create the dataloader script seacrowd/sea_datasets/my_dataset/my_dataset.py (please use only lowercase and underscore for dataset naming).
• Provide values for the _CITATION, _DATASETNAME, _DESCRIPTION, _HOMEPAGE, _LICENSE, _URLs, _SUPPORTED_TASKS, _SOURCE_VERSION, and _SEACROWD_VERSION variables.
• Implement _info(), _split_generators() and _generate_examples() in dataloader script.
• Make sure that the BUILDER_CONFIGS class attribute is a list with at least one SEACrowdConfig for the source schema and one for a seacrowd schema.
• Confirm dataloader script works with datasets.load_dataset function.
• Confirm that your dataloader script passes the test suite run with python -m tests.test_seacrowd seacrowd/sea_datasets/<my_dataset>/<my_dataset>.py.
• If my dataset is local, I have provided an output of the unit-tests in the PR (please copy paste). This is OPTIONAL for public datasets, as we can test these without access to the data files.

[ryanignatius]

reviewed and tested,
LGTM

[yongzx]

The dataloader runs (data = load_dataset("seacrowd/sea_datasets/ijelid/ijelid.py")) without needing to specify config name. Is this intended? @ljvmiranda921

[yongzx]

reviewed and tested as well.

[ljvmiranda921]

Thanks for the reviews @ryanignatius and @yongzx !
As for the load_dataset question, it automatically loads the DEFAULT_CONFIG_NAME (in this case, ijelid_souce) when nothing's passed to the name parameter.