This change makes a bunch of improvements to the new tips feature in the

review dialog:

Adds a hide button to allow people to hide the tips. While it's

  probably good for new users, experienced users likely won't want it

  cluttering up their screen. The preference for this is stored in a

  cookie
Moves the tips box to the top of the review dialog.
Changes it so the tips box is always visible, even when there's review

  content.
Adds new content to the tips list (thanks Michelle!).

Toggled the tips view back and forth.
Checked that the tips view shows up in the right place.
Verified that the initial tips view visibility respects the stored

  preference.
Ran unit tests.
Ran js-tests.