proxy server in userspace mode consumes ports that have not been properly allocated from the resource offer

[jdef]

proxy listens on random ports:

https://github.com/GoogleCloudPlatform/kubernetes/blob/release-0.14/pkg/proxy/proxier.go#L497

we probably want to introduce a port allocator interface:

type PortAllocator interface {
  Alloc() (int, error)
  Free(int)
}

and update the proxy to use it. Probably two initial implementations:

1. RandomAllocator : Alloc() always returns 0, Free() is a noop
2. RangesAllocator : allocates ports from a spec'd mesos Range resource

[jdef]

upstream support has landed for configuring the proxy port range

[jdef]

this issue does not refer to the node ports support kube-proxy, but instead to the allocation scheme implemented by the userspace proxy module in kube-proxy. see discussion in #791

placing this on hold for now.