Update numpy from 1.14.3 to 1.14.4

requirements.txt

 Dijkstar==2.4.0
 freezegun==0.3.10
 future==0.16.0
-numpy==1.14.3
+numpy==1.14.4
 pluggy==0.6.0
 psutil==5.4.4
 py==1.5.3