This commit adds CSRF protection based on the gorilla/csrf package.
Node dependencies have been updated.
Logging uses sirupsen/logrus for log level support now.
This commit adds a simple go backend calling openssl ca to sign CRS
coming from the client. The JavaScript code in src/index.html has been
extended to send requests to the sign endpoint and display the resulting
certificate in a separate div element.
A script setup_example_ca.sh and an openssl configuration file ca.cnf
has been added to allow quick setup of a simple example CA.
