Track restored version

[michaelnatkin]

Super-helpful gem; works so nicely with associations it solved my problems right out of the box. I know you aren't actively developing it right now, but if you ever come back to it, a great addition would be to keep track of which revision is currently active, i.e. if I do:

my_model.restore_revision!(7)

then I could ask:

my_model.active_revision() # => 7