Changing between units.

[Asasello]

So, there is error when user change between units:

1. First case ( starts with unit set to lbs)
   -user set weight to 1lbs
   -user set unit to kg
   -now we get 0.5 kg weight which we can not normally set ( normally when we set weight using kg minimum is 1 kg)
2. Second case (starts with unit set to kg)
   -user set weight to 300 kg
   -user set unit to lbs
   -now we get 660 lbs weight which we can not normally set (normally when we set weight using lbs maximum is 300lbs).