The Circle CI configuration is outdated for Darwin. Also, there are open issues
with N-API to deal with here: https://github.com/node-webrtc/node-webrtc/pull/672

As such, it's difficult to get a clean build at the moment (and it will take
longer to fix some known segmentation fauls). Therefore, for the time being,
this release (since it changes only `package.json`) will just reuse binaries
from the v0.4.6 release. I've made the update in S3 manually.