Allow custom key for localstorage

[dhwang]

When choosing localstorage, it would help if we can use a custom key to store the session instead of the default "USER-SESSION". For example, "[email protected]"

[redheadedstep]

I would like this also. We run multiple react apps on a single domain, each with a different login (like admin, manager, and user logins).

If we could pass in the key name as an option, that would be invaluable.