[WIP] Proposal for bundle standards document

I was going to propose this document at the IRC meeting. 

I propose that this document list all the standardizations that CMF bundles - and all bundles that are to be included in 1.0 should adhere to these standards before release.

The document is incomplete and I am also making an additional standardization proposition - the adoption of the concept of "Advanced" and "Simple" implementations - simple implementations would be the bare minimal for a thing to work, advanced would implement all features that the CMF provides (PWFC, Multilang, etc). The `Menu` and `MultilangMenu` are candidates for adopting this.

**Once merged, @dbu promised to update CONTRIBUTING.md**