WIP: auto-scaler proposal

## Abstract
Auto-scaling is a data-driven feature that allows users to increase or decrease capacity as needed by controlling the 
number of pods deployed within the system automatically.  

## Motivation

Applications experience peaks and valleys in usage.  In order to respond to increases and decreases in load, administrators 
scale their applications by adding computing resources.  In the cloud computing environment this can be 
done automatically based on statistical analysis and thresholds.

[Proposal](https://github.com/pweil-/kubernetes/blob/0bd1cfb7b15c3717c6787bdc5dba16fce79544d4/docs/proposals/autoscaling.md)
Seems like this should be of the same form as the ObjectReference used by ReplicationController to refer to a PodTemplate for #170 in v1beta3. There's an open question of whether we should change that to a URL or URI path to facilitate greater extensibility.