Attaching the storage module in `vmListenerHOC` means it can propagate
down to the GUI, stage, and blocks naturally. The default VM property
value has been removed from those places so that we're not instantiating
extra VM instances any more. Instead, using one of those components
outside of the `vmListenerHOC` framework will require providing a VM
instance as a property.

Resolves #16

/ht @rschamp

Change Toolbox Categories to match new design color

The inline css method gives us nothing that CSS modules can't give us. This puts the project more in line with the way www works, and makes CSS actually readable.

Using class names gives us full control of the modal styles.

These were named inconsistently in scratch-vm

So that it's easier to use these standalone.

And use instanceOf for the vm prop type

Move behavior-related components to "containers", leave presentation components in "components".

Confine the logic for adding/removing event listeners between the VM and the components to the relevant components.  While this tightens the coupling between the component and the environment, it makes using the individual components more self-contained.

Update webpack config and vm usage to match updates in scratch-vm

Also make the toolbox actually get used by scratch-blocks, and update the import of scratch-blocks to use the new shimming method.

This way we can have a consistent style for Node and web code.

Add skeleton toolbox component

Thanks to babel-loader and babel-eslint, we can use the same linting everywhere.  This makes our imports easier since we don't need to think about the extension.

Also export things more succinctly in src/index.js