0.2.0a0

This is the first alpha release of the v0.2.X series.

Compared to v0.1, mirdata v0.2.0a0 has a new loader: TinySOL (#165). TinySOL is a dataset of 2478 samples, each containing a single musical note from one of 14 different instruments.

Furthermore, @rabitt has added a new data type in mirdata called utils.MultipitchData, which is compatible with mir_eval's multipitch.evaluate function. This addition fixes issue #101: "medleydb_melody melody3 type not in mir_eval format".

Lastly, @magdalenafuentes made improvements to the documentation.