Add bitcask bugfix to 1.1.1 release notes
Add bitcask bugfix to 1.1.1 release notes

GabrielNicolasAvellaneda/riak,elkingtonmcb/riak,biddyweb/riak,amyvmiwei/riak,authbox-lib/riak,DavidAlphaFox/riak,basho/riak,glickbot/riak,laurenrother/riak,planobe/riak,xuejianhai/riak,planobe/riak,yangchengjian/riak