Don't ask for a Two Factor Authentication code in gitlab-ee on a frequently used browser

Description

When logging in to gitlab-ee and gitlab.com, I'm asked for a Two Factor Authentication(TFA) code EVERY login. On Amazon/Google etc I can suppress this on frequently accessed browsers.

Allow a trusted browser to not require a TFA code when the user selects.

Proposal

Allow a user to choose to not be prompted for a TFA code, if they logged in recently and choose to trust this browser. They aren't prompted

Links / references

The current dashboard of GitLab.com when logging in:

Screenshot_2017-06-30_00.46.10

Amazon permits this feature:

Screenshot_2017-06-30_00.46.25

Documentation blurb

Overview

Allow a user to trust a browser.

It would avoid a user having to constantly enter a TFA code after login on a browser that has been used before.

This would make TFA more usable, and less difficult.

Use cases

Improved update of Two Factor Security

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.