[PATCH 0 of 3 ] largefiles: addremove fixes

[Matt Harbison]

The first patch is a resend of the code I sent during the freeze, but with the test properly qrefreshed.  The second and third patches attempt to solve the same problem (enabling largefiles after opting in, but before the first commit).  I think they are both desirable together because they allow opting in at different times in the history of a repo.  I know additional switches aren't added lightly, but it seems like patch 3 is the proper way to setup a repo if the user knows beforehand they want largefiles (and it simplifies things for them later).  Patch 2 is just to fill the gap if the user already has inited the repo without the option in patch 3.