Normalize "phenomic(/lib/*)" public API

[MoOx]

Currently some stuff are in "phenomic/lib/*" and since #432 we introduced an utility in "phenomic" itself.
When we will rely on webpack 2, it will be safe to make move lib/* interfaces as exported value in "phenomic".
We will have one exception to handle for the loader name that must be a string to a pass, but we can export the string too (eg: import { contentLoader } from "phenomic" and later use a template string in webpack config).
We will have to warn and deprecate all lib/* interfaces (move lib to another place, create a lib that require new files + warn when imported).

[MoOx]

I did some stuff about that in #698, but in order to finish this, we will need webpack 2 #421 to be able to serve client and static lib from the same package (otherwise, client build will have everything, and that's too much).

[MoOx]

This is not finished yet :)

[MoOx]

Will revisit while doing the monorepo #598