BigchainDB Web Proxy to add headers to requests

Currently, the requests from public websites (like
`bigchaindb.com/getstarted` and tutorials.bigchaindb.com/crab) cannot have the
app_id and app_key required to access IPDB in the web page.

We pass such requests through a web proxy that adds the required headers
to any POST requests from `*.bigchaindb.com`.

k8s/nginx-https-web-proxy/container/Dockerfile

@@ -0,0 +1,8 @@
+FROM openresty/openresty:alpine
+RUN apk update \
+    && apk upgrade \
+    && apk add bash
+COPY nginx.conf.template /etc/nginx/nginx.conf
+COPY nginx_entrypoint.bash /
+EXPOSE 443
+ENTRYPOINT ["/nginx_entrypoint.bash"]