Use writer instead of transform

[broccoli-transform](https://github.com/joliss/broccoli-transform) is deprecated and it is recommended to use [broccoli-writer](https://github.com/broccolijs/broccoli-writer) instead. This PR makes the change and improves consistency in spacing and variable/function naming. It also removes an unnecessary (and in some cases harmful) dependency on the broccoli module.