Added --broadcast-whitelist option

[thusser]

I added a new --broadcast-whitelist option that in principle is just a copy of --whitelist but works on the broadcaster, i.e. only hosts from a given network can subscribe to its events. It just denies clients to connect, so another Comet session with the --remote flag set to that broadcaster will try to connect forever (although in increasing intervals). This is not ideal, but I don't see a nice way around it.

I also fixed a minor but in broker.py, where log.warning is used instead of log.warn.

[jdswinbank]

Thank you for this! My initial thought is that the code looks good; I'll dive into it further as soon as I get chance.

Can you confirm what the copyright status of this code is? Are you willing and able to assign copyright to me, or do you/your employer need to be mentioned in the project's licensing statement?

[thusser]

It was a minor change, so yes, you can have the copyright for it. I (or my employer) don't need to be explicitly named in the licensing statement, but of course I'd appreciate seeing my name as a contributor somewhere. It's really up to you.

[jdswinbank]

Thank you! I'm reviewing this code today. Of course, I'm delighted to list you as a contributor. Currently, the only details I have for you are the name "thusser" and the e-mail address in your git commits. If you'd like me to add a full name, URL, etc, please send it my way.

[jdswinbank]

(Actually, I see your GitHub profile now has a full name -- pretty sure it didn't last time I looked -- so I'll use that.)

[thusser]

Just name and email is fine. And yes, I updated my profile only a couple of days ago.

[jdswinbank]

I've already merged your bug fix to master and pushed it into a new release -- many thanks!

I like the broadcaster whitelisting feature. However, I think we can make it a bit simpler, because there's no real need to make a new factory class: we can just reuse the existing WhitelistingFactory. I'd also prefer to call it "subscriber whitelist" rather than "broadcast whitelist", because I think that's a little easier for new users to follow.

Starting from your commit, I've made those changes and added some docs and tests. The result is on PR #41. Could you please take a look and check if you're happy with these changes? Thanks!

[jdswinbank]

Merged #41. Please reopen this if that doesn't scratch your itch!