store the RPCPort when host is added

https://jira.zenoss.com/browse/CC-447

DEMO1:
```
# plu@plu-9: serviced host add plu-9:4979 default
570a276e
```

DEMO2:
```
# plu@plu-9: serviced host list
ID		POOL		NAME	ADDR		RPCPORT		CORES	MEM		NETWORK
570a276e	default		plu-9	10.87.110.39	4979		12	33659494400	172.17.0.0/255.255.0.0
```

DEMO3:
```
# plu@plu-9: serviced host list --verbose
[
   {
     "ID": "570a276e",
     "Name": "plu-9",
     "PoolID": "default",
     "IPAddr": "10.87.110.39",
     "RPCPort": 4979,
     "Cores": 12,
     "Memory": 33659494400,
     "PrivateNetwork": "172.17.0.0/255.255.0.0",
     "CreatedAt": "2014-11-12T20:50:36.37781999Z",
     "UpdatedAt": "2014-11-12T20:50:36.37781999Z",
     "IPs": [
       {
         "HostID": "570a276e",
         "IPAddress": "10.87.110.39",
         "InterfaceName": "eth0",
         "MACAddress": "18:03:73:3f:b5:d8"
       }
     ],
     "KernelVersion": "#47-Ubuntu",
     "KernelRelease": "3.13.0-24-generic",
     "ServiceD": {
       "Version": "0.10.0-dev",
       "Date": "Wed Nov 12 20:22:49 UTC 2014",
       "Gitcommit": "22ce1bf-dirty",
       "Gitbranch": "develop",
       "Giturl": "",
       "Buildtag": "0"
     },
     "MonitoringProfile": {
       "MetricConfigs": null,
       "GraphConfigs": null,
       "ThresholdConfigs": null
     },
     "DatabaseVersion": 4
   }
 ]
```