Add documentation for request/response filters.

[rosston]

The code supports some (undocumented) request/response filters. So add some documentation about the filters!

[rosston]

Looks like npm install is busted for node 0.6 and 0.8. I promise my documentation change doesn't fail any tests! :stuck_out_tongue_winking_eye:

[bithavoc]

We should remove 0.6 and 0.8 from the test matrix, no point in supporting such old versions. I wonder if this requires a major version bump.

[rosston]

You could maybe get away with not bumping the major version and claim that 1.x requires >= 0.10, considering that 1.x isn't actually published to npm. But I suppose master still technically has

"engines": {
    "node": ">=0.6.0"
}

I was actually planning on opening an issue soon about publishing 1.x to npm.

[bithavoc]

@rosston I just made you collaborator, please make the according changes and let me know your NPM user, I may be able to add as collaborator there as well.

[rosston]

Awesome, thank you so much! I'm rosston on npm too.

What do you think about the version for dropping 0.6 and 0.8? I'd think it probably makes sense to bump to 2.x. It's not like there's any real harm to bumping the version.

[bithavoc]

@rosston you're now collaborator in NPM.js along with @floatingLomas

I like your idea of restricting it via engines, and since the published version is 0.x I think we could start using 1.x.

Can you add a note in the readme for this too?

Thanks.

[rosston]

Sure thing! So here's what I plan to do tonight (I'm in UTC -5):

1. Merge this PR
2. Drop 0.6 and 0.8 from the Travis configuration, and add node > 0.12 (4 and maybe 5?)
3. Assuming node 4 (and 5, if available) pass on Travis, I'll update the readme to specify that the "latest branch" in the readme supports node >= 0.10
4. Tag 1.2.0 (seems like this should at least be a minor bump, right?) and publish it to npm

Does that all sound good?

[bithavoc]

Great plan!