add dev requirement

dev_requirement.txt

@@ -0,0 +1,32 @@
+astroid==2.3.3
+autopep8==1.5
+backcall==0.1.0
+decorator==4.4.2
+humanize==2.2.0
+ipykernel==5.2.0
+ipython==7.13.0
+ipython-genutils==0.2.0
+isort==4.3.21
+jedi==0.16.0
+jupyter-client==6.1.2
+jupyter-core==4.6.3
+lazy-object-proxy==1.4.3
+mccabe==0.6.1
+netaddr==0.7.19
+openvpn-api==0.1.3
+openvpn-status==0.2.1
+parso==0.6.2
+pexpect==4.8.0
+pickleshare==0.7.5
+prompt-toolkit==3.0.5
+ptyprocess==0.6.0
+pycodestyle==2.5.0
+Pygments==2.6.1
+pylint==2.4.4
+python-dateutil==2.8.1
+pyzmq==19.0.0
+six==1.14.0
+tornado==6.0.4
+traitlets==4.3.3
+wcwidth==0.1.9
+wrapt==1.11.2