[SPARK-1970] Update unit test in XORShiftRandomSuite to use ChiSquareTest from commons-math3

Updating the chisquare unit test in XORShiftRandomSuite to use the ChiSquareTest in commons-math3 instead of hardcoding the chisquare statistic for the desired confidence interval.

Author: Doris Xin <doris.s.xin@gmail.com>

Closes #1073 from dorx/math3Unit and squashes the following commits:

da0e891 [Doris Xin] remove math3 from common pom
9954143 [Doris Xin] merge master
c19948f [Doris Xin] Merge branch 'master' into math3Unit
8f84f19 [Doris Xin] [SPARK-1970] unit test in XORShiftRandomSuite
ffea61a [Doris Xin] SPARK-1939: Refactor takeSample method in RDD
1441977 [Doris Xin] SPARK-1939 Refactor takeSample method in RDD to use ScaSRS
HOTFIX: Fixing style error introduced by 08d0ac
[SPARK-2061] Made splits deprecated in JavaRDDLike

The jira for the issue can be found at: https://issues.apache.org/jira/browse/SPARK-2061
Most of spark has used over to consistently using `partitions` instead of `splits`. We should do likewise and add a `partitions` method to JavaRDDLike and have `splits` just call that. We should also go through all cases where other API's (e.g. Python) call `splits` and we should change those to use the newer API.

Author: Anant <anant.asty@gmail.com>

Closes #1062 from anantasty/SPARK-2061 and squashes the following commits:

b83ce6b [Anant] Fixed syntax issue
21f9210 [Anant] Fixed version number in deprecation string
9315b76 [Anant] made related changes to use partitions in python api
8c62dd1 [Anant] Made splits deprecated in JavaRDDLike