Investigate using TravisCI for build script

[dmsnell]

Using GitHub pages is convenient because it will automatically build the site's site files on each commit to the gh-pages branch. However, this also limits our ability to use functionality not provided by GitHub. The downside of using extensions is that we have to manually build the site and then checkin those files.

It might be possible to create a basic TravisCI script to build the files once we checkin to this branch, removing the need to rely on GitHub to automatically generate the site while keeping the flow simple for people wanting to make contributions without learning the whole build process.