a Bayou implementation with a master for test
http://dl.acm.org/citation.cfm?id=224070
Terry, D. B., Theimer, M. M., Petersen, K., Demers, A. J., Spreitzer, M. J., and Hauser, C. H. Managing update conflicts in Bayou, a weakly connected replicated storage system. SOSP 1995.