从PostgreSQL 9.3.5升级到9.4.0后，我将通过
清理以前的版本brew cleanup postgresql
但是当想要开始使用新版本的PostgreSQL时出现错误：
relrin at MacBook-Relrin in ~ exited 127
=> psql
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
好的，请尝试重启postgre：
relrin at MacBook-Relrin in ~
=> lunchy stop postgre
/Library/Ruby/Gems/2.0.0/gems/lunchy-0.8.0/lib/lunchy.rb:138: warning: Insecure world writable dir /usr in PATH, mode 040777
/usr/local/Cellar/postgresql/9.4.0/homebrew.mxcl.postgresql.plist: Could not find specified service
stopped homebrew.mxcl.postgresql
如何解决最后一个问题，我可以使用数据库？