Added ISO 639-2/T codes to i18n in addition to the ISO 639-1 codes (to support requirements for dcterms.language).
Change i18n code for ISO 639-2 lang codes to %lang-code-iso-639-2.
Merge pull request #1506 from pjackson28/v3.0

Added ISO 639-2/T codes to i18n in addition to the ISO 639-1 codes (to support requirements for dcterms.language)