This changed considered all instances of "ReviewDb" in .java files. Many
of the comments changed, but there are exceptions:
* Comments referencing old ReviewDb behavior in order to explain why
things work a certain way in NoteDb.
* Some TODO comments suggesting that we do something different after
removing ReviewDb. Eliminating these would require actual code
changes.
Change-Id: I18c0ac4038ae98aa3b9eabe4e68e23b6516ea3e8
b397acf45e