Implement allocate and deallocate of hosts. 
    1. Implement Tracker util/class which consists of 
        1. allocate(hostType) - takes host type, it’s string of alphabets and returns the first available instance index for 
        ex: if type is apibox it should return 1, 2 etc, if it’s sitebox it should return 1, 2. 
        2. deallocate(hostType, index) - this takes the type and index as arguments and deallocates.
        Deallocated instance is available for allocation under same host type