Clean up helm deployer

[huyhg]

• [ ] Copy charts unarchived in Dockerfile. Right now we're tarring them before copying onto the image. This helps the deployer not having to extract them out at deployment time.
• [x] Get rid of the .template file. Parameterization in helm should be done via values.yaml file instead.

[huyhg]

Part of #5

[huyhg]

Closed in favor of https://github.com/GoogleCloudPlatform/marketplace-k8s-app-tools/issues/167