Update CHANGELOG for 3.9.2-otc-pre4
Update CHANGELOG for 3.9.2-otc-pre4

billCTG/braintree_ios,apascual/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios,apascual/braintree_ios,billCTG/braintree_ios,apascual/braintree_ios,apascual/braintree_ios,braintree/braintree_ios,braintree/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios,braintree/braintree_ios,Feverup/braintree_ios,braintree/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios