[Feature Request] Allow searching by tag #2282

So for the search bar in the picture below:

<img width="263" alt="screenshot 2018-08-10 14 28 40" src="https://user-images.githubusercontent.com/2191808/43982188-b9c9e3f4-9ca9-11e8-9d76-564f62b84af3.png">

Can we also add a "tag" keyword in the search bar that will only return results with the given tag, like this:

<img width="309" alt="screenshot 2018-08-10 14 31 06" src="https://user-images.githubusercontent.com/2191808/43982278-0c8d54cc-9caa-11e8-9daf-9bf63aa415d8.png">

I'm flexible about the UI. For example, there can even have a special "tags" field.