New Login Mechanism

[jleandroperez]

We may have use-cases in which Simperium needs to be started with an authToken obtained by going through a flow that might not be in our control.

Right now, the only way to do this is by doing...:

self.simperium.authenticationEnabled = NO;
// Start Simperium...
self.simperium.user = [[SPUser alloc] initWithEmail:email token:simperiumToken];
[self.simperium performSelector:@selector(startNetworkManagers) withObject:nil];

Note that the 'startNetworkManagers' method is private, and the developer needs to inject, externally, an instance of SPUser. Let's update our API so no external hacks are needed:

self.simperium.authenticationEnabled = NO;
// Start Simperium...
[self.simperium authenticateWithEmail:email token:token];

[jleandroperez]

Let's update the API so email is not required.