Initial Travis CI script

This adds a Travis-compatible script that will always succeed (it just runs `echo "Works great."`). It does know to install Node 0.10.x in a VM first, even though the script doesn't make use of it.

The `script` command could be changed to run anything meaningful that returns a 0 exit code on success and a 1 on failure. `script` is an array field that can list and run multiple commands that all need to succeed for the build to be considered a success.

Once merged, go to https://travis-ci.org/profile/18F (authorize your GitHub account with Travis if you need to) and click the on/off switch next to the Sendak repo. It should Just Work.