BAMI should address uncontrolled transaction creation (DoS attack)

[devos50]

A particular weakness of TrustChain is that there is no defence against users that aim to deplete computer resources of others through a DoS attack, e.g., through the unsolicited dissemination of messages to others. While this particular issue is currently not high on the priority list, BAMI should contain a basic mechanism that blocks/ignores users that are suspected to perform a DoS attack.