[web] Support dict payload for POST requests
[tools] Drop the lock() method from WillieMemory

We have an attribute named lock, everyone is already using it.
You can't have an attribute and a method with the same name like this.
[safety] Add a new module to warn against malicious URLs in a channel

This module uses the VirusTotal API right now. Support for additional
services / blacklists will be added in the future.