update to allow passing args to tap

[patrick-rodgers]

This update allows the passing of an argument variable through to the lambda method. The argument can be a single value, array, or object - it is naively passed to the lambda. This addresses issue #17.

function myFunc(file, t, n, arg) {
//    arg === { t: 1 }
}

// gulp pipe omitted ...
tap(myFunc, { t: 1 })

Updated to also allow this:

function myFunc(file, t, n, arg, arg2, arg3) {
//    arg === { t: 1 }
// arg2 === "foo"
// arg3 === "bar"
}

// gulp pipe omitted ...
tap(myFunc, { t: 1 }, "foo", "bar")

[dotnetCarpenter]

@patrick-rodgers Thank you very much for your contribution. Will you please add two tests for this?

Bonus if you have a use-case you can link to so we can put it in the wiki and write about the motivation for this feature in the next release.

Thanks

[patrick-rodgers]

Added the tests to cover calling tap with 0, 1, or 2 args. As for a usecase you can have a look at where I used it in a task to build docs. I needed to grab the header and footer for each article and wanted to only get them once to pass them on to the function to create the html article.

[patrick-rodgers]

Oh, and all the tests pass, but please do have a look as CoffeeScript is new to me so always possible I am not actually calling anything :)