core/storage: rename module data to storage container

[b1lly]

I'm going to do a bigger refactor to the storage.

The ideas are:

1. The storage will have n number of StorageContainer instead of ModuleData
2. Each container, will be referenced by an "index" in the storage instead (e.g StorageKey = Index)
3. Each StorageContainer will have the ability to be globally set, or partially set.

For instance,

// Update the entire index.
core.storage.set(StorageIndex.GLOBAL, {
   ...
});

// Adds or updates a key in the existing index
core.storage.set(StorageIndex.GLOBAL, 'myKey', { });

// Returns the entire index
core.storage.get('StorageIndex.GLOBAL);

// Returns a key within the index
core.storage.get(StorageIndex.GLOBAL, 'myKey');

I think this will help us organize things better, as well as support the namespacing pattern we've been using. Instead of attaching Namespaces to the index as a string, we just use the keys as the namespace within the index.

So for instance, it would be used like:

core.storage.get(StorageIndex.AUTOCOMPLETE, 'namespace')

Thoughts before I implement?