Use actual test datasets

[vadixidav]

We should probably attempt to get the datasets for everything here. These datasets are small, so we will also need some larger data sets. These could be generated just using OpenCV using ORB and AKAZE or using SIFT with binarization.

[vadixidav]

There is now a scripts/generate.py that can be ran to generate a file of AKAZE descriptors from any set of images. This can be used to generate a file of AKAZE descriptors quickly from the Kitti dataset. The recall example allows the use of the -f flag to run the recall graph generator on the generated file of AKAZE descriptors.

More work ongoing to get the small datasets from ANN Benchmarks.