NaiveBayesClassifier Bug Fixes/Code organization

-Fixed a bug in NaiveBayesClassifier where the classify function with
cuda did not work properly(d_fp and d_sp were allocated as int and not
long double)
-Added #define for each of the functions of the NaiveClassifier (disable
or enable CUDA versions by commenting CUDA_CLASSIFY or CUDA_LIKELIHOOD)
-Thread per block size for each function can be adjusted in Cfg.h
-Added CudaStd class that contains all functions needed for cuda
implementations