Add travis with lint and tests

[jirwin]

What

Start using travis-ci for CI. Use jscs for lint, and run npm test for tests.

Why

CI helps speed up development with automatic validation of incoming Pull Requests. Using a linter makes a consistent code style for readability and catching simple and common bugs.

Lint details

Using jscs this implements mostly the airbnb javascript style. The differences are:

• 4 spaces for indentation instead of 2
• camelCase isn't required for Object properties
• self is the accepted keyword for storing context across closures instead of _this
• Don't require a single var statement per scope