Notify users on login via e-mail

[frjo]

Fixes #3549

Test Steps

• Check that user receives en e-mail on login.
• Check that the e-mail content is correct and informative.

[wes-otf]

This also works well & looks nice - is there a way to skip this when hijack/"switch user" is utilized? not a huge deal but would be nice to not send a notification for that

[frjo]

This also works well & looks nice - is there a way to skip this when hijack/"switch user" is utilized?

This I missed! No e-mail should be send in these cases I think, will take a look at that.