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.

I'm not sure how well this shows up in JavaDoc. Can you test it out? 

We might need to add the java @Deprecated, and then explain it has been deprecated since 1.0.1. (it is not 0.9.2).