WP-4387 Added update to enable metatag_twitter_cards and metatag_opengraph modules.
WP-4387 Added gsb_feature_megatag module to make
WP-4387 Added gsb_feature_megatag module to update
WP-4387 Added gsb_feature_metatag module to dependences
WP-4387 Fixed typo in last commit.
Add 4.0 release branch of gsb_feature_metatag.