Let coders specify minimum star rating for reviewers

[davearonson]

As a coder,
I want to specify a minimum rating for my reviewer,
So I can get a good review.

Given that there is a PR specifying a minimum of two stars to review it,
And I am logged in as a one-star reviewer,
And I am otherwise eligible to review this PR,
When I search the list,
I will not see it.
When I log in as a two-star reviewer,
And I am otherwise eligible to review this PR,
When I search the list,
I will see it.

(This might be a Premium feature.)