Install cfssl such that it shows up in package manager

If installing `cfssl` on ubuntu/debian, we would like to have it be listed when we run `dpkg -l`.
This would be really helpful in times when we need to get a list of installed packages for open-source licensing requirements or legal requirements.

**Solution Options**
- Release a `deb` package when releasing `cfssl` so we can install that.
For example,
> wget https://dl.influxdata.com/telegraf/releases/telegraf_1.10.1-1_amd64.deb
sudo dpkg -i telegraf_1.10.1-1_amd64.deb
- Make `cfssl` available to be installed via `apt install`.