splitting the core

This is a heavy one. Perhaps the heaviest. Massive changes on mean.js + dislocation of aggregation into a separate module. Currently the module is local, and required by
require('./aggregation')
but frees the mean.js from all the internal variable bindings, and - splits the core!
Expecting a thorough discussion to see how this might fit into the overall mean.io roadmap.
ReferenceError: crypto is not defined
    at Aggregator.addInlineCode (/tmp/aaa/node_modules/meanio/lib/aggregation.js:58:13)

`require('crypto')` missing