[#744] Port fixes from Akka to HashedWheelTimer

port fix from Akka with following commits:
* https://github.com/akka/akka/commit/cb4e3536b0ed3483bd3636d7789c0ddcadafa2da
* https://github.com/akka/akka/commit/7e590f3071bdf89a4aa9d7d262bac8923d85e754

And also use constants for worker state for time instead of numeric.