Fixes: 209: introduce SERF_RPC_ADDR to do the same as the -rpc-addr parameter
command-line args takes precedence over the environment
trying to figure out why travis fails

I was testing my code with this docker container: https://index.docker.io/u/crosbymichael/golang/
and worked fine, so i suspect maybe test are failing only with 'tip'
checking travis for going to 'tip' from go version 1.2.1 breaks the build