Expose host labels

[LLParse]

Exposing non-rancher host labels is useful in many cases. It helps users understand their topology at a glance.

For example, Docker Swarm:

Jamess-MacBook-Pro:cli joliver$ for f in $(env|grep DOCKER|cut -d= -f1); do unset $f; done
Jamess-MacBook-Pro:cli joliver$ rancher host
ID        HOSTNAME         STATE     IP               LABELS          DETAIL
1h76      james-10acre-1   active    10.240.0.5       swarm=master    
1h77      james-10acre-2   active    10.240.0.6       swarm=manager   
1h79      james-10acre-4   active    10.240.0.13      swarm=manager   
1h80      james-10acre-5   active    10.240.0.40                      
1h81      james-10acre-6   active    10.240.0.32                      
1h82      james-10acre-7   active    146.148.93.243
Jamess-MacBook-Pro:cli joliver$ rancher --host 1h77 docker node ls
ID                           HOSTNAME        STATUS  AVAILABILITY  MANAGER STATUS
0p2308mvfgq340ycib33e6iay    james-10acre-7  Ready   Active
1tuxzn94d73hl308mru10snye *  james-10acre-1  Ready   Active        Leader
3kndicps7o0jw7cnroetwv9rv    james-10acre-2  Ready   Active        Reachable
5bphx97jtkl2t5ehr1kh5lpap    james-10acre-5  Ready   Active
5hv5ke5qeqplnursujlw9hore    james-10acre-4  Ready   Active        Reachable
adbhevj2v8wqmcp0sqb3vuemg    james-10acre-6  Ready   Active
Jamess-MacBook-Pro:cli joliver$ rancher --host 1h77 docker service create --name redis --replicas=7 redis:3.0.6
a76bdbs6w9jqsf1q7kls1v070
Jamess-MacBook-Pro:cli joliver$ rancher --host 1h77 docker service ls
ID            NAME   REPLICAS  IMAGE        COMMAND
a76bdbs6w9jq  redis  7/7       redis:3.0.6

[ibuildthecloud]

@LLParse can you squash the commits?

[LLParse]

done