[SPARK-4964] [Streaming] Exactly-once semantics for Kafka

Author: cody koeninger <cody@koeninger.org>

Closes #3798 from koeninger/kafkaRdd and squashes the following commits:

1dc2941 [cody koeninger] [SPARK-4964] silence ConsumerConfig warnings about broker connection props
59e29f6 [cody koeninger] [SPARK-4964] settle on "Direct" as a naming convention for the new stream
8c31855 [cody koeninger] [SPARK-4964] remove HasOffsetRanges interface from return types
0df3ebe [cody koeninger] [SPARK-4964] add comments per pwendell / dibbhatt
8991017 [cody koeninger] [SPARK-4964] formatting
825110f [cody koeninger] [SPARK-4964] rename stuff per TD
4354bce [cody koeninger] [SPARK-4964] per td, remove java interfaces, replace with final classes, corresponding changes to KafkaRDD constructor and checkpointing
9adaa0a [cody koeninger] [SPARK-4964] formatting
0090553 [cody koeninger] [SPARK-4964] javafication of interfaces
9a838c2 [cody koeninger] [SPARK-4964] code cleanup, add more tests
2b340d8 [cody koeninger] [SPARK-4964] refactor per TD feedback
80fd6ae [cody koeninger] [SPARK-4964] Rename createExactlyOnceStream so it isnt over-promising, change doc
99d2eba [cody koeninger] [SPARK-4964] Reduce level of nesting.  If beginning is past end, its actually an error (may happen if Kafka topic was deleted and recreated)
19406cc [cody koeninger] Merge branch 'master' of https://github.com/apache/spark into kafkaRdd
2e67117 [cody koeninger] [SPARK-4964] one potential way of hiding most of the implementation, while still allowing access to offsets (but not subclassing)
bb80bbe [cody koeninger] [SPARK-4964] scalastyle line length
d4a7cf7 [cody koeninger] [SPARK-4964] allow for use cases that need to override compute for custom kafka dstreams
c1bd6d9 [cody koeninger] [SPARK-4964] use newly available attemptNumber for correct retry behavior
548d529 [cody koeninger] Merge branch 'master' of https://github.com/apache/spark into kafkaRdd
0458e4e [cody koeninger] [SPARK-4964] recovery of generated rdds from checkpoint
e86317b [cody koeninger] [SPARK-4964] try seed brokers in random order to spread metadata requests
e93eb72 [cody koeninger] [SPARK-4964] refactor to add preferredLocations.  depends on SPARK-4014
356c7cc [cody koeninger] [SPARK-4964] code cleanup per helena
adf99a6 [cody koeninger] [SPARK-4964] fix serialization issues for checkpointing
1d50749 [cody koeninger] [SPARK-4964] code cleanup per tdas
8bfd6c0 [cody koeninger] [SPARK-4964] configure rate limiting via spark.streaming.receiver.maxRate
e09045b [cody koeninger] [SPARK-4964] add foreachPartitionWithIndex, to avoid doing equivalent map + empty foreach boilerplate
cac63ee [cody koeninger] additional testing, fix fencepost error
37d3053 [cody koeninger] make KafkaRDDPartition available to users so offsets can be committed per partition
bcca8a4 [cody koeninger] Merge branch 'master' of https://github.com/apache/spark into kafkaRdd
6bf14f2 [cody koeninger] first attempt at a Kafka dstream that allows for exactly-once semantics
326ff3c [cody koeninger] add some tests
38bb727 [cody koeninger] give easy access to the parameters of a KafkaRDD
979da25 [cody koeninger] dont allow empty leader offsets to be returned
8d7de4a [cody koeninger] make sure leader offsets can be found even for leaders that arent in the seed brokers
4b078bf [cody koeninger] differentiate between leader and consumer offsets in error message
3c2a96a [cody koeninger] fix scalastyle errors
29c6b43 [cody koeninger] cleanup logging
783b477 [cody koeninger] update tests for kafka 8.1.1
7d050bc [cody koeninger] methods to set consumer offsets and get topic metadata, switch back to inclusive start / exclusive end to match typical kafka consumer behavior
ce91c59 [cody koeninger] method to get consumer offsets, explicit error handling
4dafd1b [cody koeninger] method to get leader offsets, switch rdd bound to being exclusive start, inclusive end to match offsets typically returned from cluster
0b94b33 [cody koeninger] use dropWhile rather than filter to trim beginning of fetch response
1d70625 [cody koeninger] WIP on kafka cluster
76913e2 [cody koeninger] Batch oriented kafka rdd, WIP. todo: cluster metadata / finding leader