[SPARK-7652] [MLLIB] Update the implementation of naive Bayes prediction with BLAS

JIRA: https://issues.apache.org/jira/browse/SPARK-7652

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #6189 from viirya/naive_bayes_blas_prediction and squashes the following commits:

ab611fd [Liang-Chi Hsieh] Remove unnecessary space.
ddc48b9 [Liang-Chi Hsieh] Merge remote-tracking branch 'upstream/master' into naive_bayes_blas_prediction
b5772b4 [Liang-Chi Hsieh] Fix binary compatibility.
2f65186 [Liang-Chi Hsieh] Remove toDense.
1b6cdfe [Liang-Chi Hsieh] Update the implementation of naive Bayes prediction with BLAS.