Use Object.prototype.hasOwnProperty instead of using hasOwnProperty directly

[wanderer]

Node's QueryString lib can and will give us objects that do not have or override hasOwnProperty. See here When that happens waterline will crash. This PR fixes that.

[wanderer]

also cleaned up a spelling error I made in the docs

[joonhocho]

what kind of library overrides hasOwnProperty and why?
And why is the code double checking hasOwnProperty in the first place anyway?
Object.keys(obj) already gives you all enumerable properties that are owned by an object.
Unless the obj itself is modified during the callback, it shouldn't be necessary.

[joonhocho]

Oh, I see "delete obj[property]". That is why it is double checking.

[wanderer]

@joonho1101 one reason you would might want override hasOwnProperty in a library is when you are dealing with hashes of raw data. For example query strings. what would happen with you wanted to parse a url like www.test.com/?hasOwnProperty=nope into an object?

[joonhocho]

I see it now. Good example. Thanks :)