Right now, our Travis CI matrix consists of 16 different configurations. It's quite huge and scary.

I don't think it's time for us to reduce the supported version range of Node.js, so that leaves the form-data and encoding options. Two questions:

1. Do we still want to continue supporting and testing on form-data v1.x? If not, then we can drop FORMDATA_VERSION=1.0.0 editions. This will shave 50% off the build jobs.
2. Can we merge the ENCODING=yes and non-encoding runs into one? E.g., run the tests without encoding first, then npm i encoding, then run the tests again, all on one machine. This will also shave 50% off the number of build jobs.

/cc @bitinn