Fix arguments for hevercardable helper

We should pass person object to the hovecrardable helper. In the
current case `this` is the status message, not the status
author. So, let's pass `author` instead of `this`.
Tests for hovercard in reshares

Coverage with tests is necessary for every feature
Use capybara hover method in the hovercard steps

Let's use methods provided by capybara whenever possible.
Make step name more logical
Make feature consistent with other features.

Actually, I just trying to make this feature pass.