refactor: rename assert -> rtts-assert
chore: transpile deps from es6+ source

Eventually we will use es6, but I need to setup es6 build for all the deps.
chore: use deps from sources (di, rtts-assert)
chore: fix es6 build
chore(deps): watchtower, expressionist from master
chore: add scripts for hacking on deps
fix: use document.createDocumentFragment()

So that it works on all browsers.