Optimized adservice Image Size (#67)
Optimized adservice Image Size (#67)

* adservice: Reduced docker image size to ~165MB
(down from ~886MB) by switching to alpine and
using multi stage builds

* adservice: Changed install of glibc in builder to not require untrusted packages

* adservice: Refactored Dockerfile to be a multi stage build. The 'build' step runs from openjdk:8-slim, but the final image is alpine based. We can get away from this since java runs in a vm & the architecture of the images doesn't change between biuld steps

GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/cloud-ops-sandbox,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/microservices-demo,GoogleCloudPlatform/cloud-ops-sandbox