Fix example code in README
Fix example code in README

variable name
410Labs/aerogear-ios-oauth2,danielpassos/aerogear-ios-oauth2,danielpassos/aerogear-ios-oauth2,aerogear/aerogear-ios-oauth2,410Labs/aerogear-ios-oauth2,OpenStack-mobile/aerogear-ios-oauth2,aerogear/aerogear-ios-oauth2,OpenStack-mobile/aerogear-ios-oauth2