added support for custom elements and namespaces

[maxnowack]

resolves #31

[austinpray]

+1

[dylang]

Thank you for doing this! I'm currently traveling with my wife in Istanbul, I hope to merge this when I return in a couple days.

[dylang]

Can you change this to:

Object.keys(data.custom_namespaces).forEach(function(name) {
    _attr['xmlns:' + name] = data.custom_namespaces[name];
});

It's a little more functional-style and there won't be a name variable left behind.

[maxnowack]

done :)

[dylang]

I've merged but I'm about to leave for the airport for an 11-hour flight so I don't want to publish until I'm back on the ground in case there are any problems.

[stuartromanek]

Not to be a bother but any update on publishing this?

[rv-kip]

I've been developing against this PR w/o issue. I did find a couple of minor documentation issues which I corrected in PR #37. Nothing that would delay publishing this though.

[dylang]

@stuartromanek Thanks for the nuge - I finally published as 1.1.0!

@rv-kip Thanks for this PR, I've rebuilt the tests using tape, hopefully cleaning them up to make it easier to add new tests. The xml it compares it is now stored in separate xml files that I hope to eventually parse and lint as part of the tests. I'll discuss more in #37.

[stuartromanek]

@dylang Awesome! Thanks!