Adding has pr label for related issues

[saulotoledo]

There are several issues that already have people working on them. It would be easier to find an issue to contribute if we did not have to look one by one. It is possible to do that by adding a "has pr" label as, for example (Angular Material 2):
https://github.com/angular/material2/labels/has%20pr

While looking at the issues list, we could just skip these issues, or choose them to review.

[ibennetch]

I think that's a great suggestion.

[saulotoledo]

@ibennetch I am closing this issue since the has-pr label was already created.

[ibennetch]

Indeed, I should have closed it myself three months ago — thank you.