Merge pull request #2503 from ncfrey/molnet-docs

1. Open an `issue`_ to discuss the dataset you want to add to MolNet.

2. Implement a function in the `deepchem.molnet.load_function`_ 

   module following the template function `deepchem.molnet.load_function.load_dataset_template`_.

   Specify which featurizers, transformers, and splitters (available from

   `deepchem.molnet.defaults`_) are supported for your dataset. 

2. Write a `DatasetLoader` class that inherits from `deepchem.molnet.load_function.molnet_loader._MolnetLoader`_ and implements a `create_dataset` method. See the `_QM9Loader`_ for a simple example.

3. Add your load function to `deepchem.molnet.__init__.py`_ for easy importing.

3. Write a `load_dataset` function that documents the dataset and add your load function to `deepchem.molnet.__init__.py`_ for easy importing.

4. Prepare your dataset as a .tar.gz or .zip file. Accepted filetypes include CSV, JSON, and SDF.

5. Ask a member of the technical steering committee to add your .tar.gz or .zip file 

   to the DeepChem AWS bucket. Modify your load function to pull down the dataset from AWS.

5. Ask a member of the technical steering committee to add your .tar.gz or .zip file to the DeepChem AWS bucket. Modify your load function to pull down the dataset from AWS.

6. Submit a [WIP] PR (Work in progress pull request) following the PR `template`_.

6. Add documentation for your loader to the `MoleculeNet docs`_.

7. Submit a [WIP] PR (Work in progress pull request) following the PR `template`_.

BACE Dataset

.. _`datasets already available in MolNet`: http://moleculenet.ai/datasets-1

.. _`Contribution guidelines`: https://github.com/deepchem/deepchem/blob/master/CONTRIBUTING.md

.. _`issue`: https://github.com/deepchem/deepchem/issues

.. _`_QM9Loader`: https://github.com/deepchem/deepchem/blob/master/deepchem/molnet/load_function/qm9_datasets.py

.. _`deepchem.molnet.load_function.molnet_loader._MolnetLoader`: https://github.com/deepchem/deepchem/blob/master/deepchem/molnet/load_function/molnet_loader.py#L82

.. _`deepchem.molnet.load_function`: https://github.com/deepchem/deepchem/tree/master/deepchem/molnet/load_function

.. _`deepchem.molnet.load_function.load_dataset_template`: https://github.com/deepchem/deepchem/blob/master/deepchem/molnet/load_function/load_dataset_template.py

.. _`deepchem.molnet.defaults`: https://github.com/deepchem/deepchem/tree/master/deepchem/molnet/defaults.py

.. _`deepchem.molnet.__init__.py`: https://github.com/deepchem/deepchem/blob/master/deepchem/molnet/__init__.py

.. _`MoleculeNet docs`: https://github.com/deepchem/deepchem/blob/master/docs/source/api_reference/moleculenet.rst

.. _`template`: https://github.com/deepchem/deepchem/blob/master/.github/MOLNET_PR_TEMPLATE.md

ZINC15 Datasets