Number: Create initial module

Implement integer and fraction digits format

Allow Globalize.format() to override locale for the following options:
- Minimum integer digits `minimumIntegerDigits`;
- Minimum fraction digits `minimumFractionDigits`;
- Maximum fraction digits `maximumFractionDigits`;

Number format setup is performed by numberFormatProperties(). Number
format execution is performed by numberFormat(). This arrangement allows
subsequent setup caching for improved performance. Yet this
implementation doesn't follow ECMA-402, it's been based on
Intl.NumberFormat instance properties.

It accepts the following `round` options:
- "ceil";
- "floor";
- "round" (default);
- "truncate";

Ref gh-200
Closes gh-209, gh-213