Open browser when debugging flask/django

https://code.visualstudio.com/updates/v1_33#_automatically-open-a-uri

We just need to configure the default debug configuration

<img width="785" alt="Screen Shot 2019-04-04 at 10 35 25 PM" src="https://user-images.githubusercontent.com/1948812/55605569-fc51b680-5729-11e9-88d2-065f74692811.png">
