Update CHANGELOG.
Update CHANGELOG.

billCTG/braintree_ios,billCTG/braintree_ios,braintree/braintree_ios,braintree/braintree_ios,billCTG/braintree_ios,billCTG/braintree_ios,billCTG/braintree_ios,braintree/braintree_ios,braintree/braintree_ios