Fix 220: Create plural module

[rxaviers]

Borrow santhoshtr/CLDRPluralRuleParser.

Ref #220

• Implementation (basically a wrapper);
• Unit tests;
• Build;
• Functional tests;
• Docs;

[jzaefferer]

Can you move the second line comment above this line? Same for the other. Also make it more explicit, e.g. "Remove UMD outro"

[rxaviers]

Ready for review (or to be landed).

A good summary of the changes made by this PR can be seen in the README diff. It creates one more module called globalize/plural.js. This new module depends on Globalize core globalize.js (and cldr.js) and nothing else (note that santhoshtr/CLDRPluralRuleParser is embedded totaling 1.9kb minified+gziped). Prior to using the pural module, one needs to load cldr/supplemental/plurals.json data. It implements both .formatPlural( value, messageData [, formatValue ] ) (more information) and .plural( value ) (more information) methods.

[jzaefferer]

Would be good to use these "output comments" consistently. Either put them after the line in question, before, or on the same line, but don't mix it, like here and with the three above.

Same for the other method.

[rxaviers]

yeap. done.

[jzaefferer]

No need for the empty message argument, its optional. The API docs for wrong until a week ago.

[rxaviers]

Thanks @jzaefferer, I've updated it based on your comments.

[jzaefferer]

This should provide a decent error message:

Globalize.formatPlural(2, { one: "{0} thing" })

Instead I get TypeError: Cannot read property 'replace' of undefined. It should tell me which plural form it used.

This uses the value instead of the empty string:

// "2 things"
Globalize.formatPlural(2, { other: "{0} things" }, "")

[rxaviers]

Thanks @jzaefferer, both fixed and covered by new functional tests.