fixes CC-460: pass rpcport to master.AddHost

https://jira.zenoss.com/browse/CC-460

DEMO:
```
I1113 19:51:02.394987 26890 agent.go:51] local static ips [] [0]
I1113 19:51:02.410187 26890 host.go:144] building with ipsAddrs: [10.87.110.39] [1]
I1113 19:51:02.412188 26890 utils.go:133] looking for '10.87.110.39'
I1113 19:51:02.412645 26890 cpserver.go:232] start getMasterClient ... sc.agentPort: 10.87.110.39:4979
I1113 19:51:02.412711 26890 cpserver.go:238] end getMasterClient
I1113 19:51:02.449701 26890 hostresource.go:177] Added host 570a276e
2014/11/13 19:51:02 200 56.296216ms POST /hosts/add
```