Common/Makefile
Common/tests/Makefile
VocabLearn/Makefile
VocabLib/tests/Makefile
* Set up correctly the compilation directives for controlling verbose of
FileUtils functions and methods.

VocabLearn/VocabLearn.cpp
* Fixed some comments to make the code more comprehensive.

VocabLib/include/VocabTree.h
* Fixed bug in method computeClustering, wrong retrieval of cv::Mat row,
it uses a zero based index and not a one based index.