Add v1.5.7 to CHANGELOG
Add v1.5.7 to CHANGELOG
mickdwyer/Hystrix,justinjose28/Hystrix,mickdwyer/Hystrix,justinjose28/Hystrix,justinjose28/Hystrix,wangsan/Hystrix,wangsan/Hystrix,wangsan/Hystrix,eunmin/Hystrix,eunmin/Hystrix,mattrjacobs/Hystrix,mattrjacobs/Hystrix,eunmin/Hystrix,mattrjacobs/Hystrix,Netflix/Hystrix,mickdwyer/Hystrix,ianynchen/Hystrix