Please document minimum versions of ember-cli and ember-cli-babel.

[Gaurav0]

It seems we are not compatible with ember-cli 2.18 and ember-cli-babel 5.1.7

[ef4]

Yes, we should document these, or better yet throw a helpful error when we see them.

But also note this is a weird combination. ember-cli 2.18 shipped with ember-cli-babel ^6.6.0, so using it with babel 5 was already a less-well-tested combination even back when ember-cli 2.18 was current and supported.

[brkn]

What's the known minimum compatible version of ember-cli?

[ef4]

We test against 2.18.