Remove "No handlers could be found for logger "gensim.models.word2vec".

Fix piskvorky#910 (piskvorky#925)

gensim/models/word2vec.py

@@ -100,6 +100,7 @@
 from types import GeneratorType
 
 logger = logging.getLogger(__name__)
+logging.basicConfig(format='%(asctime)s : %(levelname)s : %(message)s')
 
 
 try:
@@ -278,6 +279,14 @@ def train_sg_pair(model, word, context_index, alpha, learn_vectors=True, learn_h
     return neu1e
 
 
+def sigmoid(p):
+    if p > 0:
+        return 1. / (1. + exp(-p))
+    elif p <= 0:
+        return exp(p) / (1 + exp(p))
+    else:
+        raise ValueError
+
 def train_cbow_pair(model, word, input_word_indices, l1, alpha, learn_vectors=True, learn_hidden=True):
     neu1e = zeros(l1.shape)