https://issues.apache.org/jira/browse/SPARK-1483

From the original JIRA: " The parameter name is part of the public API in Scala and Python, since you can pass named parameters to a method, so we should name it to this more descriptive term. Everywhere else we refer to "splits" as partitions." - @mateiz

Author: CodingCat <zhunansjtu@gmail.com>

Closes #430 from CodingCat/SPARK-1483 and squashes the following commits:

4b60541 [CodingCat] deprecate defaultMinSplits
ba2c663 [CodingCat] Rename minSplits to minPartitions in public APIs