SPARK-2712 - Add a small note to maven doc that mvn package must happen ...

Per request by Reynold adding small note about proper sequencing of build then test.

Author: Stephen Boesch <javadba@gmail.com>

Closes #1615 from javadba/docs and squashes the following commits:

6c3183e [Stephen Boesch] Moved updated testing blurb per PWendell
5764757 [Stephen Boesch] SPARK-2712 - Add a small note to maven doc that mvn package must happen before test
(cherry picked from commit f8cd143b6b1b4d8aac87c229e5af263b0319b3ea)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
SPARK-2246: Add user-data option to EC2 scripts

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

Closes #1186 from douglaz/spark_ec2_user_data and squashes the following commits:

94a36f9 [Allan Douglas R. de Oliveira] Added user data option to EC2 script
(cherry picked from commit a0bcbc159e89be868ccc96175dbf1439461557e1)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-2197] [mllib] Java DecisionTree bug fix and easy-of-use

Bug fix: Before, when an RDD was created in Java and passed to DecisionTree.train(), the fake class tag caused problems.
* Fix: DecisionTree: Used new RDD.retag() method to allow passing RDDs from Java.

Other improvements to Decision Trees for easy-of-use with Java:
* impurity classes: Added instance() methods to help with Java interface.
* Strategy: Added Java-friendly constructor
--> Note: I removed quantileCalculationStrategy from the Java-friendly constructor since (a) it is a special class and (b) there is only 1 option currently.  I suspect we will redo the API before the other options are included.

CC: mengxr

Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>

Closes #1740 from jkbradley/dt-java-new and squashes the following commits:

0805dc6 [Joseph K. Bradley] Changed Strategy to use JavaConverters instead of JavaConversions
519b1b7 [Joseph K. Bradley] * Organized imports in JavaDecisionTreeSuite.java * Using JavaConverters instead of JavaConversions in DecisionTreeSuite.scala
f7b5ca1 [Joseph K. Bradley] Improvements to make it easier to run DecisionTree from Java. * DecisionTree: Used new RDD.retag() method to allow passing RDDs from Java. * impurity classes: Added instance() methods to help with Java interface. * Strategy: Added Java-friendly constructor ** Note: I removed quantileCalculationStrategy from the Java-friendly constructor since (a) it is a special class and (b) there is only 1 option currently.  I suspect we will redo the API before the other options are included.
d78ada6 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-java
320853f [Joseph K. Bradley] Added JavaDecisionTreeSuite, partly written
13a585e [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-java
f1a8283 [Joseph K. Bradley] Added old JavaDecisionTreeSuite, to be updated later
225822f [Joseph K. Bradley] Bug: In DecisionTree, the method sequentialBinSearchForOrderedCategoricalFeatureInClassification() indexed bins from 0 to (math.pow(2, featureCategories.toInt - 1) - 1). This upper bound is the bound for unordered categorical features, not ordered ones. The upper bound should be the arity (i.e., max value) of the feature.

(cherry picked from commit 2998e38a942351974da36cb619e863c6f0316e7a)
Signed-off-by: Xiangrui Meng <meng@databricks.com>