Add requests to requirements.txt

requirements.txt

@@ -1,9 +1,12 @@
 appnope==0.1.0
 bleach==2.1.2
+certifi==2018.1.18
+chardet==3.0.4
 cycler==0.10.0
 decorator==4.2.1
 entrypoints==0.2.3
 html5lib==1.0.1
+idna==2.6
 ipykernel==4.8.0
 ipython==6.2.1
 ipython-genutils==0.2.0
@@ -34,6 +37,7 @@ python-dateutil==2.6.1
 pytz==2017.3
 pyzmq==16.0.4
 qtconsole==4.3.1
+requests==2.18.4
 scipy==1.0.0
 Send2Trash==1.4.2
 simplegeneric==0.8.1
@@ -42,6 +46,7 @@ terminado==0.8.1
 testpath==0.3.1
 tornado==4.5.3
 traitlets==4.3.2
+urllib3==1.22
 wcwidth==0.1.7
 webencodings==0.5.1
 widgetsnbextension==3.1.3