Use grasp to transform the traceur output
Add a Travis CI configuration file
Remove Grasp wrapper dependency

With the new version of Grasp, you don't need to have a wrapper – you can just
call it with Grasp.replace().
Export underscore

We're using a transformation that absolutely needs underscore (as we're extending the global `this` with the local `this` from the anonymous function), which will fail if we don't export underscore.
Merge branch 'master' into add-grasp

Conflicts:
	package.js
	plugin/compile-harmony.js