Number Format: 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”

Add out-of-range error check for formatNumber options.

Closes #283
Number Format: Improve tests

- Assert range validations;
- Use getOptions for all numberFormat options. So, range validation is
  precisely reported in case user uses 0 (zero) for [1, 21] range
  options, eg. minimumIntegerDigits;
- Minor documentation change;

Ref #283