MS-459 update version number to 1.8
MS-459 update version number to 1.8

appnexus/mobile-sdk-ios,8tracks/appnexus-mobile-sdk-ios,appnexus/mobile-sdk-ios,8tracks/appnexus-mobile-sdk-ios,appnexus/mobile-sdk-ios,appnexus/mobile-sdk-ios,8tracks/appnexus-mobile-sdk-ios,appnexus/mobile-sdk-ios,8tracks/appnexus-mobile-sdk-ios,8tracks/appnexus-mobile-sdk-ios,appnexus/mobile-sdk-ios