LoadBalancing.java's binary search can be improved

[piyushmh]

https://github.com/epibook/epibook.github.io/blob/master/solutions/java/src/main/java/com/epi/LoadBalancing.java#L12

The left end of the binary search is currently initialised to 0 where as it can be initially set to Math.ceil(sumOfAllBytes / numServers) since this is the lower bound for the server load.