Added VirtualRESTServiceClient/VirtualRESTService classes

* Reference handling cleanup for loops in MultiHttpClient
* Support a slightly more convenient request array format for MultiHttpClient
* Added missing license header to MultiHttpClient

Change-Id: Icc86ed9e4c2ac78363aa7b6f3147253bb59e2afb
Merge "Added VirtualRESTServiceClient/VirtualRESTService classes"