fix ios 9/ iphone 6 sizing MA-1470
fix ios 9/ iphone 6 sizing MA-1470

Ben21hao/edx-app-ios-enterprise-new,edx/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-new,proversity-org/edx-app-ios,appsembler/edx-app-ios,Ben21hao/edx-app-ios-new,proversity-org/edx-app-ios,edx/edx-app-ios,edx/edx-app-ios,proversity-org/edx-app-ios,appsembler/edx-app-ios,yrchen/edx-app-ios,proversity-org/edx-app-ios,appsembler/edx-app-ios,edx/edx-app-ios,proversity-org/edx-app-ios,edx/edx-app-ios,edx/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,yrchen/edx-app-ios,proversity-org/edx-app-ios,edx/edx-app-ios,appsembler/edx-app-ios,Ben21hao/edx-app-ios-new,appsembler/edx-app-ios,yrchen/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-new,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-new