Setup integration with Travis CI

[rclarkburns]

• Setup a .travis.yml template file that will be used to create a project .travis.yml when setting up a project
• Template should install dependencies
• Template should run ./scripts/cibuild
• ./scripts/cibuild should execute tests and linting, etc.
• Non-zero exit from cibuild script will cause build to fail and update PR

[rclarkburns]

Example .travis.yml (https://github.com/ManifoldScholar/manifold/blob/master/.travis.yml)