Confirmation System should not be able to spam

[JessyCat92]

As Spam protection there should be limits implemented:

• Only generate new code every 5 Minutes OR after already used
• Do not send more emails as one every 5 Minutes
• Exception could be per purpose (one email change, one password forgotten etc.)

Should have effect for:

• Reimplement Password forgotten functionallity #6
• Reimplement Basic Login #5