Add a Spam checking API

Example usage from script:

{{velocity}}
$services.antispam.isSpam("simple", "test content world", {'ip' : $request.getRemoteAddr()})
{{/velocity}}

Can be configured by:

• Adding an AntiSpam.IPAddresses page with a list of IP addresses (one per line)
• Adding an AntiSpam.Keywords page with a list of spam keywords/tokens (can be several words and there's support for regex syntax too)