fix the numpy version has to be lower than 1.15 (#12523)

* fix the numpy version has to be lower than 1.15

* Add TODO comments

python/requirements.txt

 requests==2.9.2
-numpy>=1.12
+numpy>=1.12,<=1.14 #TODO:change to ">=1.12" when numpy fix bug in 1.15 and higher version
 protobuf==3.1
 recordio>=0.1.0
 matplotlib