[SPARK-2495][MLLIB] make KMeans constructor public

to re-construct k-means models freeman-lab

Author: Xiangrui Meng <meng@databricks.com>

Closes #2112 from mengxr/public-constructors and squashes the following commits:

18d53a9 [Xiangrui Meng] make KMeans constructor public
SPARK-2798 [BUILD] Correct several small errors in Flume module pom.xml files

(EDIT) Since the scalatest issue was since resolved, this is now about a few small problems in the Flume Sink `pom.xml`

- `scalatest` is not declared as a test-scope dependency
- Its Avro version doesn't match the rest of the build
- Its Flume version is not synced with the other Flume module
- The other Flume module declares its dependency on Flume Sink slightly incorrectly, hard-coding the Scala 2.10 version
- It depends on Scala Lang directly, which it shouldn't

Author: Sean Owen <sowen@cloudera.com>

Closes #1726 from srowen/SPARK-2798 and squashes the following commits:

a46e2c6 [Sean Owen] scalatest to test scope, harmonize Avro and Flume versions, remove direct Scala dependency, fix '2.10' in Flume dependency
SPARK-3180  - Better control of security groups

Adds the --authorized-address and --additional-security-group options as explained in the issue.

Author: Allan Douglas R. de Oliveira <allan@chaordicsystems.com>

Closes #2088 from douglaz/configurable_sg and squashes the following commits:

e3e48ca [Allan Douglas R. de Oliveira] Adds the option to specify the address authorized to access the SG and another option to provide an additional existing SG
[FIX] fix error message in sendMessageReliably

rxin

Author: Xiangrui Meng <meng@databricks.com>

Closes #2120 from mengxr/sendMessageReliably and squashes the following commits:

b14400c [Xiangrui Meng] fix error message in sendMessageReliably
Fixed a typo in docs/running-on-mesos.md

It should be `spark-env.sh` rather than `spark.env.sh`.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2119 from liancheng/fix-mesos-doc and squashes the following commits:

f360548 [Cheng Lian] Fixed a typo in docs/running-on-mesos.md
[SPARK-3204][SQL] MaxOf would be foldable if both left and right are foldable.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #2116 from ueshin/issues/SPARK-3204 and squashes the following commits:

7d9b107 [Takuya UESHIN] Make MaxOf foldable if both left and right are foldable.
[SPARK-2929][SQL] Refactored Thrift server and CLI suites

Removed most hard coded timeout, timing assumptions and all `Thread.sleep`. Simplified IPC and synchronization with `scala.sys.process` and future/promise so that the test suites can run more robustly and faster.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #1856 from liancheng/thriftserver-tests and squashes the following commits:

2d914ca [Cheng Lian] Minor refactoring
0e12e71 [Cheng Lian] Cleaned up test output
0ee921d [Cheng Lian] Refactored Thrift server and CLI suites
[SPARK-3058] [SQL] Support EXTENDED for EXPLAIN

Provide `extended` keyword support for `explain` command in SQL. e.g.
```
explain extended select key as a1, value as a2 from src where key=1;
== Parsed Logical Plan ==
Project ['key AS a1#3,'value AS a2#4]
 Filter ('key = 1)
  UnresolvedRelation None, src, None

== Analyzed Logical Plan ==
Project [key#8 AS a1#3,value#9 AS a2#4]
 Filter (CAST(key#8, DoubleType) = CAST(1, DoubleType))
  MetastoreRelation default, src, None

== Optimized Logical Plan ==
Project [key#8 AS a1#3,value#9 AS a2#4]
 Filter (CAST(key#8, DoubleType) = 1.0)
  MetastoreRelation default, src, None

== Physical Plan ==
Project [key#8 AS a1#3,value#9 AS a2#4]
 Filter (CAST(key#8, DoubleType) = 1.0)
  HiveTableScan [key#8,value#9], (MetastoreRelation default, src, None), None

Code Generation: false
== RDD ==
(2) MappedRDD[14] at map at HiveContext.scala:350
  MapPartitionsRDD[13] at mapPartitions at basicOperators.scala:42
  MapPartitionsRDD[12] at mapPartitions at basicOperators.scala:57
  MapPartitionsRDD[11] at mapPartitions at TableReader.scala:112
  MappedRDD[10] at map at TableReader.scala:240
  HadoopRDD[9] at HadoopRDD at TableReader.scala:230
```

It's the sub task of #1847. But can go without any dependency.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #1962 from chenghao-intel/explain_extended and squashes the following commits:

295db74 [Cheng Hao] Fix bug in printing the simple execution plan
48bc989 [Cheng Hao] Support EXTENDED for EXPLAIN
[SQL] logWarning should be logInfo in getResultSetSchema

Author: wangfei <wangfei_hello@126.com>

Closes #1939 from scwf/patch-5 and squashes the following commits:

f952d10 [wangfei] [SQL] logWarning should be logInfo in getResultSetSchema