Refactor PodStatus to PodCondition in internal API for v1beta3

Change PodStatus (string) to PodCondition (string) to make space for new PodStatus (struct) in v1beta3 API.

Change the constant values for Pod statuses to match v1beta3 API.
You need to randomly choose one of the valid ones (that can be round tripped).

----- Original Message -----
> > @@ -86,6 +86,9 @@ var apiObjectFuzzer =
> > fuzz.New().NilChance(.5).NumElements(1, 1).Funcs(
> >  		j.ResourceVersion = strconv.FormatUint(c.RandUint64()>>8, 10)
> >  		j.SelfLink = c.RandString()
> >  	},
> > +	func(j *api.PodCondition, c fuzz.Continue) {
> > +		*j = api.PodRunning
> 
> Not sure what you mean by this.  I had to add that Fuzzer method because the
> new conversion methods I added making valid constants required as opposed to
> arbitrary strings.  I just used "running" in the fuzzer but it could be
> any/all of them, randomly, except Failed, like you say.
> 
> ---
> Reply to this email directly or view it on GitHub:
> https://github.com/GoogleCloudPlatform/kubernetes/pull/2179/files#r19899330