Refactor article modules and bootstrap inits

Adds context/event bindings etc to liveBlogging, matchNav, reading modules. 

Init functions for common & article bootstraps are made idempotent, sort-of. The first call runs the modules, adds a listener, and fires an event; subsequent calls only fire the event.

Moves modules Ajax, Errors, Fonts, Debug from common.js into app.js bootstrap. common.js is now the place for modules that bind on each `page:ready` event.