Fix heatmap augmentation in Affine
Fix heatmap augmentation in Affine

This commit fixes two bugs in the heatmap
augmentation of Affine:
1) Affine always updates imgaug.HeatmapsOnImage.shape
   as if fit_output was True, leading to bad shapes.
2) If fit_output was True and the input to
   Affine._augment_images_by_samples() was an array,
   the augmentation could crash due to trying to assign
   an image of shape (H',W',C) to an array of shape
   ([N], H, W, C), i.e. changes H/W was not considered.

aleju/imgaug,aleju/ImageAugmenter,aleju/imgaug