[SPARK-2309][MLlib] Multinomial Logistic Regression

#1379 is automatically closed by asfgit, and github can not reopen it once it's closed, so this will be the new PR.

Binary Logistic Regression can be extended to Multinomial Logistic Regression by running K-1 independent Binary Logistic Regression models. The following formula is implemented.
http://www.slideshare.net/dbtsai/2014-0620-mlor-36132297/25

Author: DB Tsai <dbtsai@alpinenow.com>

Closes #3833 from dbtsai/mlor and squashes the following commits:

4e2f354 [DB Tsai] triger jenkins
697b7c9 [DB Tsai] address some feedback
4ce4d33 [DB Tsai] refactoring
ff843b3 [DB Tsai] rebase
f114135 [DB Tsai] refactoring
4348426 [DB Tsai] Addressed feedback from Sean Owen
a252197 [DB Tsai] first commit