the Rank list doesn't update when a new submit (with invalid repo typed in) happens

[yizongk]

The user types in a valid repo, the PR list updates, and the Rank list updates.

Then the user types in an invalid repo, the PR list updates, but the Rank list doesn't update.

A possible fix, clear the PR data variable (in Home.js) on submit.

[zhik]

Fixed #96