[SPARK-7127] [MLLIB] Adding broadcast of model before prediction for ensembles

Broadcast of ensemble models in transformImpl before call to predict

Author: Bryan Cutler <bjcutler@us.ibm.com>

Closes #6300 from BryanCutler/bcast-ensemble-models-7127 and squashes the following commits:

86e73de [Bryan Cutler] [SPARK-7127] Replaced deprecated callUDF with udf
40a139d [Bryan Cutler] Merge branch 'master' into bcast-ensemble-models-7127
9afad56 [Bryan Cutler] [SPARK-7127] Simplified calls by overriding transformImpl and using broadcasted model in callUDF to make prediction
1f34be4 [Bryan Cutler] [SPARK-7127] Removed accidental newline
171a6ce [Bryan Cutler] [SPARK-7127] Used modelAccessor parameter in predictImpl to access broadcasted model
6fd153c [Bryan Cutler] [SPARK-7127] Applied broadcasting to remaining ensemble models
aaad77b [Bryan Cutler] [SPARK-7127] Removed abstract class for broadcasting model, instead passing a prediction function as param to transform
83904bb [Bryan Cutler] [SPARK-7127] Adding broadcast of model before prediction in RandomForestClassifier