[SPARK-11440][CORE][STREAMING][BUILD] Declare rest of @Experimental items...

[SPARK-11440][CORE][STREAMING][BUILD] Declare rest of @Experimental items non-experimental if they've existed since 1.2.0

Remove `Experimental` annotations in core, streaming for items that existed in 1.2.0 or before. The changes are:

* SparkContext
  * binary{Files,Records} : 1.2.0
  * submitJob : 1.0.0
* JavaSparkContext
  * binary{Files,Records} : 1.2.0
* DoubleRDDFunctions, JavaDoubleRDD
  * {mean,sum}Approx : 1.0.0
* PairRDDFunctions, JavaPairRDD
  * sampleByKeyExact : 1.2.0
  * countByKeyApprox : 1.0.0
* PairRDDFunctions
  * countApproxDistinctByKey : 1.1.0
* RDD
  * countApprox, countByValueApprox, countApproxDistinct : 1.0.0
* JavaRDDLike
  * countApprox : 1.0.0
* PythonHadoopUtil.Converter : 1.1.0
* PortableDataStream : 1.2.0 (related to binaryFiles)
* BoundedDouble : 1.0.0
* PartialResult : 1.0.0
* StreamingContext, JavaStreamingContext
  * binaryRecordsStream : 1.2.0
* HiveContext
  * analyze : 1.2.0

Author: Sean Owen <sowen@cloudera.com>

Closes #9396 from srowen/SPARK-11440.