Added blank opencv test file
Added basic CMake script

Looks for opencv and sets c++11 options for gcc compilers
Added test image
Updated opencv test

Added code to load a test image and display it, convert it to grayscale and display the grayscale image, run edge detection on the image and display the detected edges, and find circles in the image using a hough transform and display the detected circles
Added gitignore

Ignored CMake user settings files by default