Unify core.js and run.js conventions.

[sholladay]

Before the mini core can be brought online, it needs to know how to load the target app.

To do this reasonably, we should avoid any kind of lookup table for determining the main entry point of the app. That is a slippery slope and could cause headaches related to versioning if developers feel that it's okay to change the structure because we have a lookup table.

Instead, there should be a convention for all apps that core.js is the programmatic API and run.js has a side effect that initializes the app using that API.

A reference implementation can be found in sitecues-mobile run.js and core.js.