Delete profile should Unset the current profile

[medyagh]

Delete profile should Unset the current profile

to reproduce:
1- create a minikube with profile p1 and p2

./out/minikube start -p p1 --vm-driver=hyperkit

./out/minikube start -p p2 --vm-driver=hyperkit

2- set the current profile to p1

./out/minikube profile p1

3- delete profile p1

 ./out/minikube delete -p p1
🔥  Deleting "p1" in hyperkit ...
💔  The "p1" cluster has been deleted.

4-
the current profile is gone from profile list (correctly) however if u check for current profile it shows the deleted one:

medya@ ~/workspace/ppl-minikube (fix-glog-parse-error) $ ./out/minikube profile list
|----------|-----------|----------------|-----------|--------------------|
| Profile  | VM Driver |     NodeIP     | Node Port | Kubernetes Version |
|----------|-----------|----------------|-----------|--------------------|
| minikube | hyperkit  | 192.168.64.102 |      8443 | v1.15.0            |
| p3       | hyperkit  | 192.168.64.118 |      8443 | v1.15.0            |
|----------|-----------|----------------|-----------|--------------------|

5- check for current profile

$ ./out/minikube profile
p1

The fix should, after delete unset the current config.

[josedonizetti]

/assign @josedonizetti