clustering unit test

add task ids to docs of list_tasks

# Conflicts:
#	openml/datasets/functions.py

fix docstrings in list_datasets, some pep8

Cast data qualities to float

WIP dataset Tagging

Make task the default concept to work with

…agging

Datalist status

fixes #373 + unit test

* Fix ascii decoding problem with python 2

* Created separate pickle files for splits and datasets according to the python version

* Added production task to unit test

* Update test_task_functions.py

* Implementing dataset listing with more filters and adding unit tests

* Add to function documentation

* Created first basic template, removed redudant variable

* Improving list_datasets

* First implementation of the list_* with the limit tag active

* First implementation of the feature, fixed bugs and refactored the code

* Changing batch_size to be a keyword argument

* Fixed not considering initial offset, removing size and the double offset key from the filter dict

* Changing task_type_id argument name in accordance with the new implementation

* Reverting previous solution for task_type_id, implementing another fix

* Fix for python2 and changing the unit test which times out

* Added another test method and did a slight change in an existing test method

* Changing the assert value for the failing test method

* Added the implementation to filter by uploader for flows, filter by task_type for runs, filter by multipple operator for tasks and also refactored the code according to PEP8

* Refactored code as requested

* ADD unit test to ensure example listing

* Update test_study_examples.py

* MAINT bump required liac-arff version

* Update requirements.txt

* ADD contributing guidelines and github templates

* Update CONTRIBUTING.md

* ADD reference to scikit-learn to the license

* Added clarification for unit test on Windows.

* ADD hash checks to datasets

* split target on comma, allows errors on multiple targets

* FIX unit test

* MAINT move from cell executor to exec to test jupyter notebooks

* Mock calls to /run/upload/ in notebook unit tests

* FIX mock patch target

* Change backend

* Basic solution for private datasets

* Faulty and not necessary implementation of finally

* Fixed assertRaises call in test_get_data

* Updated get_dataset

* Fixed typo

* Have different directories for different servers

* simplify based on jans comments

* fix attribute access

* Change variable name

* Take into account Jans suggestions

* Harmonize import, fix rebase errors

* re-add accidentaly removed files

* First try at a solution

* Removing faulty fix

* Fix for bug in unit test, method _get_cached_task

* Removing FileNotFoundError as it does not exist in python2

* Fixing test_tagging

* Changing id according to new solution

* Change _remove_dataset_cache_dir to the new implementation

* Adding support for home directory symbol

* Fixing backward compatibility

* ADD introductory snippet to front page of the docs

* FIX issues with rst formatting

* FIX fixes and improves unit tests

* ADD additional asserts to hunt down bug

* ADD debug output

* remove print statement

* FIX circle ci yaml file (remove requirements.txt)

* circle ci: build docs on all branches