Test: add missing html tag
Various: Use ES5, users should polyfill on their own for IE8 support

Fixes #244
Fixes #259
Fixes #260
Closes #276
Various: Create simple internal common message formatting

Ref #265
Plural: Create initial module

Borrow santhoshtr/CLDRPluralRuleParser.

Ref #220
Duration: Create it (Skeleton)

Ref #205