IPv4 rotation fix

[kikkia]

Problem

IPv4 rotation is currently broken. When the route planner tries to find a new Ip it would always pass in a 0 to the getAddressAtIndex on the ipblock. This would always return an exception (it checks if the index is 0 or lower and throws)

Solution

Remove the code in the route planner that subtracts one from the block index. This fix works for me currently using either 1 large ipv4 block, or a list of ipv4 /32 blocks. I cannot test this fix on any of the ipv6 rotation stuff.
As I am not too familiar with the code base, would this fix be better to implement on the rotator level or within the IP block? I currently changed it within the rotator as that is how my current custom implementation does it and I am not sure if changing it on the IP block level would possibly introduce some regressions.

I am happy to change this fix based on any comments/suggestions.