How do I install curl with http2 support

As of now (Jan 2018). You will have to install curl from source to get http2 support. You can do that using the following commands

sudo apt-get -y install build-essential nghttp2 libnghttp2-dev libssl-dev
wget https://curl.haxx.se/download/curl-7.63.0.tar.gz
tar xzf curl-7.63.0.tar.gz
cd curl-7.63.0
./configure --with-nghttp2 --prefix=/usr/local --with-ssl
make && sudo make install
sudo ldconfig