6.0.0

I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.

packages/babel/cli.js

@@ -0,0 +1,5 @@
+console.error("The CLI has been moved into the package `babel-cli`.");
+console.log();
+console.log("$ npm install -g babel-cli");
+console.log();
+process.exit(1);