Setup CI

A quick note to install CI.

Package to build a CI server from scratch

1. Ubuntu 16.04, sudo apt-get update && sudo apt-get install build-enssential
2. CUDA 10.0 (if upgrade the cuda version, need to update build/env.yml in every d2l-* project
3. Miniconda 3
4. Latex for PDF sudo apt-get install texlive-full librsvg2-bin
5. Fonts for PDF

   wget https://raw.githubusercontent.com/d2l-ai/utils/master/install_fonts.sh
   sudo bash install_fonts.sh