Updated JJPluralForm to 2.0 and example app.

- Allows use of custom separator beside the ';' for plural forms
- Introduces a lighter-weight +pluralStringForNumber:withPluralForms: method to be used in conjunction with +setPluralRule: and optionally, +setPluralFormsSeparator: and +setShouldLocalizeNumeral:
- Introduced enums for various plural rules for clarify
- Doxygen-style comments for all methods that can be displayed as inline help by Xcode