formatNumber to accept maximumFractionDigits=0

Logic error in the options processing that prevent
maximumFractionDigits=0 from being passed into internal methods
properly, resulting in maximumFractionDigits being set to default
value. Fixed the logic and added tests to ensure fraction truncation.

```Globalize.formatNumber(3.14159, {maximumFractionDigits: 0}) === "3"```

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Review:

- [ ] Implementation;
- [ ] [jQuery coding style](http://contribute.jquery.org/style-guide/js);
- [ ] Unit and functional tests;
- [ ] Documentation;
:+1:, please go ahead and remove the Sanity check of `number/format/integer-fraction-digits.js`, it's no longer needed after your check here.