Add the following commands:

.deserter instance add $time (Adds the instance deserter debuff with $time duration to your target)
.deserter bg add $time (Adds the BG deserter debuff with $time duration to your target)
.deserter instance remove (Removes the instance deserter debuff)
.deserter instance remove (Removes the bg deserter debuff)
Merge pull request #9388 from thomas007788/DeserterCmd

Implement .deserter commands