[SPARK-1406] Mllib pmml model export

See PDF attached to the JIRA issue 1406.

The contribution is my original work and I license the work to the project under the project's open source license.

Author: Vincenzo Selvaggio <vselvaggio@hotmail.it>
Author: Xiangrui Meng <meng@databricks.com>
Author: selvinsource <vselvaggio@hotmail.it>

Closes #3062 from selvinsource/mllib_pmml_model_export_SPARK-1406 and squashes the following commits:

852aac6 [Vincenzo Selvaggio] [SPARK-1406] Update JPMML version to 1.1.15 in LICENSE file
085cf42 [Vincenzo Selvaggio] [SPARK-1406] Added Double Min and Max Fixed scala style
30165c4 [Vincenzo Selvaggio] [SPARK-1406] Fixed extreme cases for logit
7a5e0ec [Vincenzo Selvaggio] [SPARK-1406] Binary classification for SVM and Logistic Regression
cfcb596 [Vincenzo Selvaggio] [SPARK-1406] Throw IllegalArgumentException when exporting a multinomial logistic regression
25dce33 [Vincenzo Selvaggio] [SPARK-1406] Update code to latest pmml model
dea98ca [Vincenzo Selvaggio] [SPARK-1406] Exclude transitive dependency for pmml model
66b7c12 [Vincenzo Selvaggio] [SPARK-1406] Updated pmml model lib to 1.1.15, latest Java 6 compatible
a0a55f7 [Vincenzo Selvaggio] Merge pull request #2 from mengxr/SPARK-1406
3c22f79 [Xiangrui Meng] more code style
e2313df [Vincenzo Selvaggio] Merge pull request #1 from mengxr/SPARK-1406
472d757 [Xiangrui Meng] fix code style
1676e15 [Vincenzo Selvaggio] fixed scala issue
e2ffae8 [Vincenzo Selvaggio] fixed scala style
b8823b0 [Vincenzo Selvaggio] Merge remote-tracking branch 'upstream/master' into mllib_pmml_model_export_SPARK-1406
b25bbf7 [Vincenzo Selvaggio] [SPARK-1406] Added export of pmml to distributed file system using the spark context
7a949d0 [Vincenzo Selvaggio] [SPARK-1406] Fixed scala style
f46c75c [Vincenzo Selvaggio] [SPARK-1406] Added PMMLExportable to supported models
7b33b4e [Vincenzo Selvaggio] [SPARK-1406] Added a PMMLExportable interface Restructured code in a new package mllib.pmml Supported models implements the new PMMLExportable interface: LogisticRegression, SVM, KMeansModel, LinearRegression, RidgeRegression, Lasso
d559ec5 [Vincenzo Selvaggio] Merge remote-tracking branch 'upstream/master' into mllib_pmml_model_export_SPARK-1406
8fe12bb [Vincenzo Selvaggio] [SPARK-1406] Adjusted logistic regression export description and target categories
03bc3a5 [Vincenzo Selvaggio] added logistic regression
da2ec11 [Vincenzo Selvaggio] [SPARK-1406] added linear SVM PMML export
82f2131 [Vincenzo Selvaggio] Merge remote-tracking branch 'upstream/master' into mllib_pmml_model_export_SPARK-1406
19adf29 [Vincenzo Selvaggio] [SPARK-1406] Fixed scala style
1faf985 [Vincenzo Selvaggio] [SPARK-1406] Added target field to the regression model for completeness Adjusted unit test to deal with this change
3ae8ae5 [Vincenzo Selvaggio] [SPARK-1406] Adjusted imported order according to the guidelines
c67ce81 [Vincenzo Selvaggio] Merge remote-tracking branch 'upstream/master' into mllib_pmml_model_export_SPARK-1406
78515ec [Vincenzo Selvaggio] [SPARK-1406] added pmml export for LinearRegressionModel, RidgeRegressionModel and LassoModel
e29dfb9 [Vincenzo Selvaggio] removed version, by default is set to 4.2 (latest from jpmml) removed copyright
ae8b993 [Vincenzo Selvaggio] updated some commented tests to use the new ModelExporter object reordered the imports
df8a89e [Vincenzo Selvaggio] added pmml version to pmml model changed the copyright to spark
a1b4dc3 [Vincenzo Selvaggio] updated imports
834ca44 [Vincenzo Selvaggio] reordered the import accordingly to the guidelines
349a76b [Vincenzo Selvaggio] new helper object to serialize the models to pmml format
c3ef9b8 [Vincenzo Selvaggio] set it to private
6357b98 [Vincenzo Selvaggio] set it to private
e1eb251 [Vincenzo Selvaggio] removed serialization part, this will be part of the ModelExporter helper object
aba5ee1 [Vincenzo Selvaggio] fixed cluster export
cd6c07c [Vincenzo Selvaggio] fixed scala style to run tests
f75b988 [Vincenzo Selvaggio] Merge remote-tracking branch 'origin/master' into mllib_pmml_model_export_SPARK-1406
07a29bf [selvinsource] Update LICENSE
8841439 [Vincenzo Selvaggio] adjust scala style in order to compile
1433b11 [Vincenzo Selvaggio] complete suite tests
8e71b8d [Vincenzo Selvaggio] kmeans pmml export implementation
9bc494f [Vincenzo Selvaggio] added scala suite tests added saveLocalFile to ModelExport trait
226e184 [Vincenzo Selvaggio] added javadoc and export model type in case there is a need to support other types of export (not just PMML)
a0e3679 [Vincenzo Selvaggio] export and pmml export traits kmeans test implementation