CLC-846 Proxies now partake of cache expiration (but not cache writing, yet)
CLC-846 Split CanvasProxy into 1 class per cacheable request, and make caching work for all of them
CLC-846 Cache awareness, but not writing, for Google proxy endpoints
CLC-846 Split SakaiProxy into 1 class per request, and add caching
Merge pull request #436 from ctweney/clc-846

CLC-846 Adding caching to the proxy layer, work in progress