Create a new allocator that uses the ServiceCIDRs configured in the
system to create IPAllocators.
The CIDRAllocator will create IPAllocators per parent ServiceCIDRs,
since we allow overlapping, there is no need to have an allocator
per ServiceCIDR.
The benefit of the IPAllocator is that uses the informer cache as
storage, hence, it does not need to keep cache and as only as logical
abstraction. This allows to create and delete IPAllocators without
any penalty.
IPAllocators can allocate IP addresses only if they are ready (not
being deleted)
Change-Id: I3fdda69991907c39cca3120fe2d850f14dcccec2
63fe539b4e