Object Storage via Minio

Initial check-in of Minio service, based from stable/minio version 0.4.3.

This includes:

• Adding enabled wrapper flags on the whole chart
• Implementing initContainer configuration behavior
• Removing all use of secrets values via environment variables
• Adding documentation for the changes made to the chart.
• Add support for accepting pre-existing PersistentVolume, on top of the ability to use dynamic generation.
• Alter defaultBucket behavior to accept a list of buckets, with policy and purge behaviors per-bucket.
• Changed the default of serviceType to ClusterIP in place of LoadBalancer
• Remove creation of secret, and add to documentation.
• Ensure the post-install hook waits until the service is up before attempting to create buckets.
• Move scripting in post-install hook to ConfigMap/initialize to allow better maintainability.
• Remove unused mode: shared|distributed values and surrounding logic

Todo:

• Remove secret? Static naming of cerfificate vs dynamic naming via the .Release.Name might be easier to configure. Static naming will also cause collisions if we split Object Storage buckets into multiple services in the future.
• This storage is not attached to any other chart, mostly for the above reason.
• Cleanup of the original documentation. Left intact for review purproses during WIP.

Future improvements:

• Have bucket creation post-install job wait for the service to come up prior to mc commands being executed.
• Stash logs outside of the Pod/Job

[ci skip]

Relates to #77 (closed)