Moving around.
Singleton session is now `Substance.session`.

It is better to have this variable in a namespace
to avoid inadvertent access due to programming errors.
Also, it is more descriptive and easier to find out
where the singleton is used.
Make LocalStorage based AppSettings more robust.
Removed sub-scoped for blobs in Store API.
Cleanup.
Introduce an factories to session interface.

This allows to derive a different session implemetation easily.
E.g., this is used to execute Tests with different underlying store implementation.
Generalized replicator tests.