Counter increment and decrement return value

[pbstriker38]

Current return value

irb(main):001:0> counter = Kredis.counter('my_counter', expires_in: 1.hour)
irb(main):002:0> counter.increment
=> [true, 1]
irb(main):003:0> counter.decrement
=> [false, 0]

expected return value

irb(main):001:0> counter = Kredis.counter('my_counter', expires_in: 1.hour)
irb(main):002:0> counter.increment
=> 1
irb(main):003:0> counter.decrement
=> 0

I can open a pull request if this is an acceptable change.

[dhh]

Yes please!