Action protect feature

As more and more production system uses openwhisk
Users will need some features to protect their service safe from mistake.

So there has any protect mechanism to avoid the action delete/update action by mistake?

How about like this, for example
```
wsk action delete hello --comfirm yes
wsk action update hello hello.js --comfirm yes
```
If user wants to delete/update their action, should add `--confirm yes`(or `--confirm y`).
If don't added, give below tip
```
Please delete action using --confirm yes if you really want to delete it
```