Fix the issue that invalid instance name (empty or null) can be created

[zousheng]

Fix the issue #63

[dhilipkumars]

@zousheng Thanks for the PR?

could you run
gofmt
golint
and
go vet
in the code? we could get a cleaner new code.

Also are you using redis-proxy in your project?

[zousheng]

Sure, I tried to use it in our production, and found few issues

1. I changed the proxy part to support proxy multiple redis servers, and store the mappings in the zk. In production the broken pipe issue occurred, and I added one io try catch for io.copy() method. and add the test-on-borrow on client, then it seems solved for now

2. In test environment, we tried to shutdown machine first to test the failover, it turns out master-slave failover not working, it's only working when I stop or kill the container, so this is very critical issue. Haven't checked the code yet. Would you please give some advice? Thanks