Targetran

Change default values of some parameters
- random rotate angle range: (-15.0, 15.0)
- random shear angle range: (-10.0, 10.0)
- random translate height/width range: (-0.1, 0.1)
- random crop height/width range: (0.8, 0.9)

Breaking changes: shorten some input parameter names regarding cropping, e.g., `cropped_image_height` -> `crop_height`.

Initial public release of Targetran, a data augmentation library to assist object detection or image classification model training. It can be used with TensorFlow or PyTorch.