hw4: Initial commit, folders and images
Reorganization: Moved SIFT to libs/

Added a folder, libs/, to the root of the repo.
Moved the SIFT library there.
File reorganization: Added 'common/' dir

Moved all non-hw-specific code to a new folder, 'common' (renamed libs).
Code in 'common' will be used by hw3 & hw4.
Initial code for extractTemplate

This function will eventually extract a template image from a given test
image.