Update SIFT.hpp

Added #include <opencv2/nonfree/features2d.hpp> 
SiftFeatureDetector
SiftDescriptorExtractor
Update CvSURF.hpp

Added #include <opencv2/nonfree/features2d.hpp>
for SurfFeatureDetector and SurfDescriptorExtractor declarations. 
Merge pull request #1 from qiubix/master

Poprawa CvBasic