gelam-loader -> worker-config

Confines the loader config to just the worker config. gelam-loader.js was renamed to worker-config.js, and the config is generated as an object literal config. This will mean that we can use it directly in an r.js optimization of the gelam files. The loader context was removed too, now it just uses the default context.

This means the test files have small config blocks in them now, but they just set up two or so paths that are static, not changing, if we add more dependencies later.

There is some map config trickery around addressparser since it is the one lib currently loaded on both sides of the main vs worker fence, and by doing that map config in the worker (I believe only used in test scenarios) it means the gaia email app consumption of gelam does not need special config to use gelam. gaia email does use a map config for ext/main-frame-config, but that is just out of convenience of being able to reference 'api' as the dependency ID in modules. This allows us some flexibility of then switching out the api provider to some other module provider later without touching those module dependency IDs.