Ticket reference

# What is this?

This PR adds a 17 long character reference to a ticket when it's created.

# Why is it 17 characters long?

In this case I went with the Brief provided to me. It specified a format for the string. However, if it wasn't for that I probably would have just used `SecureRandom.uuid`.

# Why are you using Friendly_id?

Friendly_id is a great gem that integrates nicely with rails and the rails paths. Does all the heavy lifting and we can just focus on the reference generation.