Add name parameter to get_proxy_status

In https://github.com/jubatus/jubatus/commit/e2746d139e2c695ac580a1681eaf109c59493148, I add `get_proxy_status` to client.hpp.

At first, I thought that `name` is not necessary to send. So, I didn't set `name`.
But, If client send `name`, it will be ignored by jubaproxy.

In this patch, I add `name` parameter to `get_proxy_status`.
I unified 2nd parameter of RPC `call` method.