fix: Fix node v4 support by using babel-preset-env

[tmcw]

Fixes #873

[coveralls]

Coverage increased (+3.9%) to 82.439% when pulling d3f381f on transform-node-4 into ffdfa21 on master.

[coveralls]

Coverage decreased (-4.6%) to 73.981% when pulling ff7a32d on transform-node-4 into ffdfa21 on master.

[coveralls]

Coverage decreased (-4.5%) to 74.037% when pulling 699e748 on transform-node-4 into ffdfa21 on master.

[coveralls]

Coverage decreased (-0.01%) to 78.532% when pulling 7b07fc0 on transform-node-4 into ffdfa21 on master.

[tmcw]

Wow, this is terrible. I think it makes more sense to just not use new JavaScript features than to go this deep into the rabbit hole. Cross-reference: jestjs/jest#3126 (comment)