Update predict leaf indices (dmlc#2135)

* Updated sklearn_parallel.py for soon-to-be-deprecated modules

* Updated predict_leaf_indices.py; Use python3 print() as other exmaples and removed unused module

Author: yang-zhang

demo/guide-python/predict_leaf_indices.py

@@ -1,5 +1,4 @@
 #!/usr/bin/python
-import numpy as np
 import xgboost as xgb
 
 ### load data in do training
@@ -12,9 +11,9 @@
 
 print ('start testing predict the leaf indices')
 ### predict using first 2 tree
-leafindex = bst.predict(dtest, ntree_limit=2, pred_leaf = True)
-print leafindex.shape
-print leafindex
+leafindex = bst.predict(dtest, ntree_limit=2, pred_leaf=True)
+print(leafindex.shape)
+print(leafindex)
 ### predict all trees
 leafindex = bst.predict(dtest, pred_leaf = True)
-print leafindex.shape
+print(leafindex.shape)