Use RDD type for `foreach` operator in Java.
Use RDD type for `transform` operator in Java.

This is an improved implementation of the `transform` operator in Java.
The main difference is that this allows all four possible types of
transform functions

1. JavaRDD -> JavaRDD
2. JavaRDD -> JavaPairRDD
3. JavaPairRDD -> JavaPairRDD
4. JavaPairRDD -> JavaRDD

whereas previously only (1) and (3) were possible.

Conflicts:

	streaming/src/test/java/spark/streaming/JavaAPISuite.java
Use RDD type for `slice` operator in Java.

This commit uses the RDD type in `slice`, making it available to both normal
and pair RDD's in java. It also updates the signature for `slice` to match
changes in the Scala API.
Small changes that were missing in merge
Merge pull request #481 from pwendell/stream-rdd-type-streaming

STREAMING-51: Add RDD type as a type parameter in JavaDStreamLike Edit (streaming/ version)