Admins can't administer personal snippets
### Summary
Admins behave like a regular user when accessing personal snippets. If a personal snippet is public, they can only comment or award emoji. If it's private, they can only view it.
### Steps to reproduce
1. As a normal user, create a personal snippet.
2. As an admin, view the snippet. You won't be able to do administer the snippet.
### What is the current *bug* behavior?
Admin can view a personal snippet but can't do anything (e.g. edit, delete, etc) on it.
### What is the expected *correct* behavior?
Admin should be able to do everything an author can do. Just like what they can do on project snippets.
### Possible fixes
Modifying the rule for author in [this policy](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/policies/personal_snippet_policy.rb) to also include `admin` condition should fix this. That way both author and admins have the same permissions on a personal snippet.
/cc @jramsay @DouweM
issue