Background: As a user, I want to be able to toggle on/off WhoWroteThat from the "Tools" sidebar, so that I can easily access (or exit) the tool's view.
• Add a link/button to toggle WhoWroteThat view on/off on the sidebar, under "Tools"
• The text of the link should read as follows: "Who Wrote That?"
• The "Who Wrote That" link should be the last in the order of tools (i.e. do not change the current order)
• If a user toggles on WWT, the WWT mode should display on an article page
• If the user toggles off WWT, the WWT mode should no longer display on an article page
• If the user attempts to load WWT on a non-article page (for example, a Talk page, User page, Edit view of an article, etc), the WWT mode should not load.