Build failure on Circle CI.

[martinhbramwell]

I tried to use this repo to make my own circle.yml, but found it had failed its last build.

On my own fork, I reverted the breaking change and built successfully.

Here's the code :
1e56f81#diff-b9cfc7f2cdf78a7f4b91a753d10865a2L14

The babel plugin transformers cannot be removed with out changes elsewhere. I did not investigate further.