Theme settings are shared between subdomains

[thibault-barrat]

What you were expecting:
If you have have two react-admin apps installed on the same domain, each app should have its own theme settings.

What happened instead:
The theme settings are stored in local storage for the domain inside the key RaStore.theme and so the settings are shared between subdomains.

[fzaninotto]

Indeed, developers should be able to specify a custom store key (instead of "RaStore") by passing a custom store.