Merge pull request #30 from buxx/pyup-scheduled-update-2018-03-26

requirements.txt

 numpy==1.14.2
 pluggy==0.6.0
 psutil==5.4.3
-py==1.5.2
+py==1.5.3
 pyglet==1.3.1
-pytest==3.4.2
-python-dateutil==2.7.0
+pytest==3.5.0
+python-dateutil==2.7.1
 PyYAML==3.12
 redis==2.10.6
 six==1.11.0