Autogenerate routes if host is not specified - based on service and namespace ala OS v{1,2}

[ramr]

Autogenerate host names (if none are specified) for routes based on service and namespace ala
openshift v{1,2}.

@pweil- PTAL
Let me know if I got this right, still a newb. There's probably some additional work to pass a config variable/value down to the API - still figuring that out - probably via kubeconfig would be the right answer, I dunno (will chat w/ you on Monday). Thanks.

Unit tests pass (make check) and integration tested this with the sample app https://github.com/ramr/origin/tree/master/examples/sample-app - removing the "host" defined for the frontend in examples/sample-app/application-template-stibuild.json and getting one to autogenerate based on the service + namespace.

[vagrant@openshiftdev sample-app]$ osc get -n test routes    
NAME                HOST/PORT                        PATH                SERVICE             LABELS    
route-edge          frontend-test.v3.openshift.com                       frontend            template=application-template-stibuild    

[smarterclayton]

Allocation (once we have shards) will be a controller and a separate process.

Turn this into a type, take this as a value passed in, and then do it that way.

[ramr]

@smarterclayton @pweil- made changes as per your comments above. PTAL

[pweil-]

I think this should occur prior to ValidateRoute. That way we can ensure that whatever is generated passes the same validation as a user submitted name (util.IsDNSSubdomain).

[ramr]

Ok - will move it up/prior to that check.

[pweil-]

@ramr couple small things and I think it looks good unless we want to abstract an allocator object (#1250 (comment))

[pweil-]

LGTM if we're ok with waiting on extracting the interface. Tagging for e2e.

[test]

[openshift-bot]

continuous-integration/openshift-jenkins/test SUCCESS (https://ci.openshift.redhat.com/jenkins/job/test_pull_requests_openshift3/1269/)

[openshift-bot]

Evaluated for origin up to 681d13b