Improve Pip and Interpolation service helm configuration

[automatedops]

• Change values to map structure
• Not create deployment and service if service is not enabled
• Allow Pip and Interpolation service to use PVC like EBS or AWS EFS

[orangejulius]

This is really great, thanks! Give me a little while to test it out. In the mean time, some questions: :)

• Can a kubernetes cluster with kops create an EFS volume, as your comments indicate? I know it can make EBS volumes for PVCs automatically, but making EFS volumes that can be shared would be super useful
• If you want to, tell me a bit about how you're using Pelias! We're always happy to hear about people who find it useful, especially if they're using Kubernetes.

[automatedops]

By default. KOPS only configure EBS as default storage class. KOPS doesn't provide any helper functions to provision EFS volume. User has to provision EFS and setup EFS storage class before using it in this helm chart.

This is a guide to configure EFS provisioner and storage class.
https://github.com/kubernetes-incubator/external-storage/tree/master/aws/efs

User can use any Kubernetes supported storage class based on their tech stack, not just limit to EBS or EFS.

In Pelias's case, using a volume supports ReadWriteMany (like EFS, NFS, Glusterfs and etc) will be super helpful when scaling out services (especially pip and interpolation services). That reduces boot up time dramatically.

[orangejulius]

This was merged in #73, thanks!