Support concat() with Arrays

[baudehlo]

What I most often end up doing is the following:

var bufflist = [];
response.on('data', function (chunk) { bufflist.push(chunk) });
response.on('end', function () { var buf = buffertools.concat.apply(buffertools, bufflist); ... });

Which would be more efficient if you could do concat() with Arrays.

I may try and patch this in, but the C++ stuff isn't my expertise (yet). If it's easy I would suggest you do it rather than me :)