Can't set annotation with colons

```
$ kustomize edit add annotation -- project/url:http://my_awesome_project
Error: invalid annotation: project/url:http://my_awesome_project (too many colons)
...
```

```
$ kustomize version 
Version: {KustomizeVersion:2.0.1 GitCommit:ce7e5ee2c30cc5856fea01fe423cf167f2a2d0c3 BuildDate:2019-02-08T00:57:04Z GoOs:unknown GoArch:unknown}
```

:-(