Add get_status to proxy

I implemented `get_status` method to proxy.

### Interface 

* RPC method name: `get_proxy_status`
* Parameter: None
* Return value: `map<string, map<string, string>>` (same as `get_status`)

### Details of return values
* Key: Host and Port (e.g. `127.0.0.1_9199`), Value:
  * Key: PROGNAME, Value: Program name (e.g. `jubaclassifier_proxy`)
  * Key: RSS, Value: Total amount of physical memory used by process (same as `get_status`)
  * Key: SHR, Value: Amount of shared memory used by process (same as `get_status`)
  * Key: VIRT, Value: Total  amount  of virtual memory used by process (same as `get_status`)
  * Key: clock_time, Value: System clock time when receiving a request
  * Key: uptime, Value: How long the process has been running (sec)
  * Key: start_time, Value: System clock time when process started
  * Key: connected_zookeeper, Value: Host and Port of zookeeer that process connected (e.g. `127.0.0.1_2181`)
  * Key: forward_count, Value: Number of forwarding request
  * Key: request_count, Value: Number of request
  * Key: pid, Value: Process ID
  * Key: user, Value: User ID who started process
  * Key: timeout, Value: Command-line argument or default value
  * Key: interconnect_timeout, Value: Command-line argument or default value
  * Key: zookeeper_timeout, Value: Command-line argument or default value
  * Key: zookeeper, Value: Command-line argument or default value
  * Key: session_pool_expire, Value: Command-line argument or default value
  * Key: session_pool_size, Value: Command-line argument or default value
  * Key: threadnum, Value: Command-line argument or default value
  * Key: loglevel, Value: Command-line argument or default value (Converted to string like `INFO`, `FATAL` ...)
  * Key: loglevel, Value: Command-line argument or `/dev/stderr` (It's default value)

### example

In python, output of `pprint` is followings:

```
{'xx.x.xxx.xxx_9199': {'PROGNAME': 'jubaclassifier_proxy',
                       'RSS': '3668',
                       'SHR': '3056',
                       'VERSION': '0.5.0',
                       'VIRT': '734692',
                       'clock_time': '1389698052',
                       'connected_zookeeper': '127.0.0.1:2181',
                       'forward_count': '0',
                       'interconnect_timeout': '10',
                       'logdir': '/dev/stderr',
                       'loglevel': 'INFO',
                       'pid': '13987',
                       'request_count': '3',
                       'session_pool_expire': '60',
                       'session_pool_size': '0',
                       'start_time': '1389695688',
                       'threadnum': '16',
                       'timeout': '10',
                       'uptime': '2364.48',
                       'user': 'rimms',
                       'zookeeper': 'localhost:2181',
                       'zookeeper_timeout': '10'}}
```

### Note

* We should add `get_proxy_status` method to Ruby, Python, Java client.
* We should write tests of client.