Invalidate the store at logout, emptying cached items such as artists,
albums and songs and then preventing them from quickly reappearing when
reconnecting with the same or a different account.
Closes#5.
* Keep track of pagination in the store
* Use Immutable in reducers
* Finish i18n, every available strings are now translated in English and French
* Add a loading indicator
* Premises of API error handling
* Better locale negotiation
When not setting an endpoint protocol scheme at login, "http" was
assumed. Changing this to the same protocol as current one, to avoid
mixed blocked content.
Also prevent multiple submissions of LoginForm.
