re-org:

1. move SimpleTokenizer to examples
2. move LR to classification, HashingTF and StandardScaler to feature, CV and ParamGridBuilder to tuning
3. define SimpleTransformer
move ParamGridBuilder test to ParamGridBuilderSuite
remove implicit mapping from ParamMap
update StandardScaler to use SimpleTransformer
add getModel to PipelineModel
check param parent in set/get
rename SimpleTransformer to UnaryTransformer
more doc / remove HasMetricName trait
add schema transformation layer
doc changes
add @AlphaComponent to package-info
update tests
add unit test for pipeline
remove external data deps
re-org java test suites
clean up