Add Job Descriptions (from Basecamp)

This is another thing that come the visa job descriptions, I needed to list out the individual technologies for completeness, and the coupling of "Lead" and "CSS" here probably isn't accurate.

It should be an expectation that web-developers at thoughtbot can participate in the CSS, but not that it should be led. I will try to revise.

This also makes me realize that this job description is web specific and needs to be revised to take into account iOS developers.