Scikit-plot

New features:
* `plot_learning_curve` has new parameter `scoring` to allow custom scoring functions. By jengelman
* New plotting function `plot_calibration_curves`

Deprecations
* The Factory API has been deprecated and will be removed in v0.4.0
* `scikitplot.plotters` has been deprecated and the functions in the Functions API have been distributed to various new modules. See documentation for more details.

Features

* New option `hide_zeros` for `plot_confusion_matrix` by ExcaliburZero. 39
* New option to plot only certain labels in `plot_confusion_matrix` by ExcaliburZero. 41
* New options to set colormaps for `plot_pca_2d_projection`, `plot_silhouette`, `plot_precision_recall_curve`, `plot_roc_curve`, and `plot_confusion_matrix`. 50

Bugfix:
* Fixed bug with nan values in confusion matrices by ExcaliburZero (42)

Features:
* 38 adds new parameter `x_tick_rotation` to `plot_confusion_matrix` and `plot_feature_importances`

Bugfix
* Fix for 31

* Fix 13 Thanks to david1309 for pointing out the fix
* New argument `labels` for `plot_confusion_matrix`. This also fixes 28

* Previously, `plot_elbow_curve` calculated cost manually instead of using the built-in `score method of a clusterer instance.