remove inferno (bug TBD)

Inferno is out of date, and is a duplicate for the package build system we have. We actually have three build systems now:

- inferno
- Makefile (```make package```)
- gulp 

[gulp](https://github.com/mozilla/fireplace/pull/753) will win out. And fabric already bumps the newest version of the package on dev.

There is also some updates to the README that had some outdated stuff. Though I am going to write complete frontend docs on sphinx.
please don't remove this. it was very helpful before. devs already complain about not knowing where everything is and where the docs are.

and plus, I think this PR should be about only removing inferno.