Draft for Input_layer copied from Data_layer
Added input_layer to set of layers and to factory
Fixed input_layer to pass tests, added cat image to data to perform the tests
Added the option to resize_image to resize images using cv::resize while reading them
Renamed input_layer to images_layer
Fixed typos to pass test_images_layer
Enforce that new_height and new_width are both 0 or both > 0
Merge pull request #120 from sguada/images_layer

Images layer: A data provider layer directly from images