[test] setup babel for the functional tests

[spalger]

It was originally unclear how to setup babel to work with intern, but while trying to speedup the tests I worked out how to make it happen.

Now all of the test files, except for the single index file, are built with babel before being executed by intern. Additionally, no AMD wrappers or requirejs intern/dojo/node!../ prefix is needed to load node modules.

The only down-side to this change is that requiring parts of intern has to be done in a hacky way. Thankfully there are only two items that are ever required from intern, so it was simple to move those into a shared module and do the hacky stuff in two places, one on the intern side of things and another on the node side of things.

There are many benefits to this change though, but I'm most excited about the ability to use async/await. Expect a pr soon transitioning some of the tests.

[LeeDr]

Can I still run an individual test suite for one app? I used to be able to do this;

node_modules/intern/bin/intern-runner.js config=test/intern functionalSuites=test/functional/apps/discover/index

[spalger]

No, now that there is a single entry point you will need to use intern's grep option. Even though it requires a change, this has the benefit of having arbitrary granularity

[LeeDr]

LGTM