Feature: Resource allocations

**As an API consumer, I want to be able to request a resource from a named pool and allocate it to myself so that I can automatically allocate resources during service provisioning**

Right now, I imagine the allocation request would contain the following items:
- pool name
- any search criteria (attribute based) to filter which candidate resources are selected from the pool

My initial use case is allocating IP addresses and switch ports for L2VPN provisioning, but depending on the design (I haven't had a deep dive into code yet) this might be feasible for any resource type.

If this fits with the goals and designs of nsot I should have no problem contributing :)