Backend developers need Ruby

We get a lot of applications for the Developer position without any Ruby experience, which makes total sense given that the page explicitly refers to the confidence gap, but for this particular position requiring Ruby experience is not currently something we'll budge on.

When this is merged, I plan to add the following Yes/No question to the application form:

Do you have significant experience with Ruby? If not, be aware that this position strictly requires Ruby experience per https://about.gitlab.com/jobs/developer/#ruby-experience. Please refer to that section on other possible ways to join the GitLab team.