Add configuration option to report spam-type to Mollom

I would like to implement the first configuration option in the settings menu which is related to how the "report spam" link behaves. Based on this "Send detailed spam information to Mollom" setting, it would either:

- report the spam to Mollom without adding a category (would become the default)
- go to the detailed Mollom form which ask to provide Mollom with the type of spam (current behaviour)

I personally am only interested in the first behaviour, but I would still like the second behaviour to be available since it has some value for those people who can endure the additional selection phase :-)

If agreed, I will implement this.