Computed Keypoint descriptors for all images and wrote as numpy 2d arrays in txt files

Added a class for Config of the program. It is quite useful to run the
test cases on small files, or to send outputs to different directories.
@Gautham: you might want to create another similar class with your paths
and commit it to the repo, then we can simply uncomment/comment
whichever config is needed as per who is running the program.