Session: replace e-mail by verified identity ID
Session: replace e-mail by verified identity ID

The e-mail can be ambiguous to identify which VerifiedIdentity
has been used for login. This way, we know it and we know the
e-mail by fetch such instance.

Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server